Date   

Re: Close up of M81 without CCDT67

Wayne Hixson
 

Wade, AG Optical makes a f/6.7 12.5” imaging Dall-Dirkham, quartz optics, just north of 40 lbs but not collapsible. I have one all ready to jump on my Mach 2 when it arrives. 😉

Wayne


Re: Close up of M81 without CCDT67

Roland Christen
 

Let's put it this way, I am not a good enough optician to make a really great RC. I know a couple of people who can, but don't ask the price. A 10" - 12" RC made by expert hands can easily run you north of $6K - $10K for just the optics set.
If the imported RCs are of high quality with accurate figure and smooth optics, then they have achieved a real breakthrough in production and my hat's off to them.

Rolando



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Sat, Feb 15, 2020 11:47 am
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks, Roland. You said what I suspected about RC and CDK but with the expertise that I can trust and really believe.

Greg

On Feb 15, 2020, at 11:27 AM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:



Can you start making some smaller RC’s😀
RCs have two issues that prevent me from ever making them. Both primary and secondary have heavy aspheric surfaces that are extremely difficult to make smooth, and can potentially produce a lot of scattered light. The second issue is collimation which has to be very exacting.

The whole point of an RC was that it used only two reflective surfaces and did not require any refractive elements to eliminate coma, whereas a normal Classical Cassegrain and a basic Newtonian both have off-axis coma that require refractive coma correcting elements. Therefore the RC in a professional observatory could be used to provide a larger coma-free field and be able to pass all wavelengths from deep UV to far IR. The Classical Cass and Newtonian both need refractive elements which restricts the useful wavelength range.

Few people know that just because an RC eliminates coma, it does not inherently produce a sharp flat field. It still has field curvature and off-axis astigmatism, so in order to cover a wide field with pinpoint stars, it needs a field flattener with refractive elements. If that's the case, then it is actually easier to make a Classical Cass or even easier a Dall-Kirkham and do the coma-correction and field flattening with a simple refractive element near the focal plane. The D-K with its spherical secondary is miles less sensitive to mis-collimation and actually can produce a sharper flat field than an RC. The primary mirror is 4 times easier to make (and thus make well), and can be made with very smooth surfaces because of the very mild aspheric that is needed for full correction.

Rolando

-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:40 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Close up of M81 without CCDT67

Roland Christen
 

Well, sometimes I don't think things thru when i suggested tape over the edge of the mirror. That, of course is bad advise.

I may be wrong about what I am seeing in your bright stars, and it may indeed be the very high gain of your camera. Here's what I would do: just try a thin cardboard mask over the edge and compare the result with no mask. If you don't see any difference, then your edge correction is fine and you won't need to mask it down.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Sat, Feb 15, 2020 11:11 am
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks for the optics lesson. 


On Feb 15, 2020, at 9:34 AM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


Actually it is not a good idea to put any tape on the reflective surface. On the Lomo RC scopes they used a metal disc which was on standoffs that were attached to the rear cell. I would make a paper disc and carefully lay it on the edge of the mirror and attach it to the side of the mirror with Scotch tape. Being careful to not rub the aluminum surface.

Roland



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:57 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

If I were to attempt to mask the edge what kind of tape can you use that wouldn’t harm the coatings?

Robert 


On Feb 14, 2020, at 8:40 PM, Robert Chozick via Groups.Io <rchozick@...> wrote:

 Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Close up of M81 without CCDT67

Roland Christen
 

Yes, would be a sweet scope, but isn't exactly cheap to make either. There would be intense competition from overseas manufacturers.

Rolando



-----Original Message-----
From: W Hilmo <y.groups@...>
To: main <main@ap-gto.groups.io>
Sent: Sat, Feb 15, 2020 10:55 am
Subject: Re: [ap-gto] Close up of M81 without CCDT67

How about something like a 12” F/6 corrected Dall-Kirkham, light weight and can be broken down for transport like your 17”?
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Saturday, February 15, 2020 8:27 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Close up of M81 without CCDT67
 
 
Can you start making some smaller RC’s😀
RCs have two issues that prevent me from ever making them. Both primary and secondary have heavy aspheric surfaces that are extremely difficult to make smooth, and can potentially produce a lot of scattered light. The second issue is collimation which has to be very exacting.
 
The whole point of an RC was that it used only two reflective surfaces and did not require any refractive elements to eliminate coma, whereas a normal Classical Cassegrain and a basic Newtonian both have off-axis coma that require refractive coma correcting elements. Therefore the RC in a professional observatory could be used to provide a larger coma-free field and be able to pass all wavelengths from deep UV to far IR. The Classical Cass and Newtonian both need refractive elements which restricts the useful wavelength range.
 
Few people know that just because an RC eliminates coma, it does not inherently produce a sharp flat field. It still has field curvature and off-axis astigmatism, so in order to cover a wide field with pinpoint stars, it needs a field flattener with refractive elements. If that's the case, then it is actually easier to make a Classical Cass or even easier a Dall-Kirkham and do the coma-correction and field flattening with a simple refractive element near the focal plane. The D-K with its spherical secondary is miles less sensitive to mis-collimation and actually can produce a sharper flat field than an RC. The primary mirror is 4 times easier to make (and thus make well), and can be made with very smooth surfaces because of the very mild aspheric that is needed for full correction.
 
Rolando
 
-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:40 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67
Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 
 
I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   
 
Robert 
 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:

I like the resolution on that Running Man image. Very nice.
 
Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.
 
I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.
 
Rolando
 
 
 
-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67
So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?
 
I also got a shot of the Running Man with the 1600mm setup:
 
 
I got M101 at 1600 but the seeing was worse and guiding not as good. 
 
 
Robert
 
 
 
On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:
 
You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.
 
I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))
 
Rolando
 
 
 
-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67
Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  
 
Robert
 
On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:
 
That's really nice. Sharp and great color.
 
A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.
 
Rolando
 
 
 
-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67
I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.
 
 
Robert Chozick
 
 
 
 
Robert Chozick
 
 
 
 
Robert Chozick
 
 
 


Re: Close up of M81 without CCDT67

Greg Salyer
 

Thanks, Roland. You said what I suspected about RC and CDK but with the expertise that I can trust and really believe.

Greg

On Feb 15, 2020, at 11:27 AM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:



Can you start making some smaller RC’s😀
RCs have two issues that prevent me from ever making them. Both primary and secondary have heavy aspheric surfaces that are extremely difficult to make smooth, and can potentially produce a lot of scattered light. The second issue is collimation which has to be very exacting.

The whole point of an RC was that it used only two reflective surfaces and did not require any refractive elements to eliminate coma, whereas a normal Classical Cassegrain and a basic Newtonian both have off-axis coma that require refractive coma correcting elements. Therefore the RC in a professional observatory could be used to provide a larger coma-free field and be able to pass all wavelengths from deep UV to far IR. The Classical Cass and Newtonian both need refractive elements which restricts the useful wavelength range.

Few people know that just because an RC eliminates coma, it does not inherently produce a sharp flat field. It still has field curvature and off-axis astigmatism, so in order to cover a wide field with pinpoint stars, it needs a field flattener with refractive elements. If that's the case, then it is actually easier to make a Classical Cass or even easier a Dall-Kirkham and do the coma-correction and field flattening with a simple refractive element near the focal plane. The D-K with its spherical secondary is miles less sensitive to mis-collimation and actually can produce a sharper flat field than an RC. The primary mirror is 4 times easier to make (and thus make well), and can be made with very smooth surfaces because of the very mild aspheric that is needed for full correction.

Rolando

-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:40 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Close up of M81 without CCDT67

Robert Chozick
 

Thanks for the optics lesson. 


On Feb 15, 2020, at 9:34 AM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


Actually it is not a good idea to put any tape on the reflective surface. On the Lomo RC scopes they used a metal disc which was on standoffs that were attached to the rear cell. I would make a paper disc and carefully lay it on the edge of the mirror and attach it to the side of the mirror with Scotch tape. Being careful to not rub the aluminum surface.

Roland



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:57 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

If I were to attempt to mask the edge what kind of tape can you use that wouldn’t harm the coatings?

Robert 


On Feb 14, 2020, at 8:40 PM, Robert Chozick via Groups.Io <rchozick@...> wrote:

 Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Close up of M81 without CCDT67

W Hilmo
 

How about something like a 12” F/6 corrected Dall-Kirkham, light weight and can be broken down for transport like your 17”?

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Saturday, February 15, 2020 8:27 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Close up of M81 without CCDT67

 

 

Can you start making some smaller RC’s😀

RCs have two issues that prevent me from ever making them. Both primary and secondary have heavy aspheric surfaces that are extremely difficult to make smooth, and can potentially produce a lot of scattered light. The second issue is collimation which has to be very exacting.

 

The whole point of an RC was that it used only two reflective surfaces and did not require any refractive elements to eliminate coma, whereas a normal Classical Cassegrain and a basic Newtonian both have off-axis coma that require refractive coma correcting elements. Therefore the RC in a professional observatory could be used to provide a larger coma-free field and be able to pass all wavelengths from deep UV to far IR. The Classical Cass and Newtonian both need refractive elements which restricts the useful wavelength range.

 

Few people know that just because an RC eliminates coma, it does not inherently produce a sharp flat field. It still has field curvature and off-axis astigmatism, so in order to cover a wide field with pinpoint stars, it needs a field flattener with refractive elements. If that's the case, then it is actually easier to make a Classical Cass or even easier a Dall-Kirkham and do the coma-correction and field flattening with a simple refractive element near the focal plane. The D-K with its spherical secondary is miles less sensitive to mis-collimation and actually can produce a sharper flat field than an RC. The primary mirror is 4 times easier to make (and thus make well), and can be made with very smooth surfaces because of the very mild aspheric that is needed for full correction.

 

Rolando

 

-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:40 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

 

Robert 

 



On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:



I like the resolution on that Running Man image. Very nice.

 

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

 

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

 

Rolando

 

 

 

-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

 

I also got a shot of the Running Man with the 1600mm setup:

 

 

I got M101 at 1600 but the seeing was worse and guiding not as good. 

 

 

Robert

 

 

 

On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

 

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

 

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

 

Rolando

 

 

 

-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

 

Robert

 

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

 

That's really nice. Sharp and great color.

 

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

 

Rolando

 

 

 

-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.

 

 

Robert Chozick

 

 

 

 

Robert Chozick

 

 

 

 

Robert Chozick

 

 

 


Re: Close up of M81 without CCDT67

Roland Christen
 

Actually it is not a good idea to put any tape on the reflective surface. On the Lomo RC scopes they used a metal disc which was on standoffs that were attached to the rear cell. I would make a paper disc and carefully lay it on the edge of the mirror and attach it to the side of the mirror with Scotch tape. Being careful to not rub the aluminum surface.

Roland



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:57 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

If I were to attempt to mask the edge what kind of tape can you use that wouldn’t harm the coatings?

Robert 


On Feb 14, 2020, at 8:40 PM, Robert Chozick via Groups.Io <rchozick@...> wrote:

 Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Close up of M81 without CCDT67

Roland Christen
 


Can you start making some smaller RC’s😀
RCs have two issues that prevent me from ever making them. Both primary and secondary have heavy aspheric surfaces that are extremely difficult to make smooth, and can potentially produce a lot of scattered light. The second issue is collimation which has to be very exacting.

The whole point of an RC was that it used only two reflective surfaces and did not require any refractive elements to eliminate coma, whereas a normal Classical Cassegrain and a basic Newtonian both have off-axis coma that require refractive coma correcting elements. Therefore the RC in a professional observatory could be used to provide a larger coma-free field and be able to pass all wavelengths from deep UV to far IR. The Classical Cass and Newtonian both need refractive elements which restricts the useful wavelength range.

Few people know that just because an RC eliminates coma, it does not inherently produce a sharp flat field. It still has field curvature and off-axis astigmatism, so in order to cover a wide field with pinpoint stars, it needs a field flattener with refractive elements. If that's the case, then it is actually easier to make a Classical Cass or even easier a Dall-Kirkham and do the coma-correction and field flattening with a simple refractive element near the focal plane. The D-K with its spherical secondary is miles less sensitive to mis-collimation and actually can produce a sharper flat field than an RC. The primary mirror is 4 times easier to make (and thus make well), and can be made with very smooth surfaces because of the very mild aspheric that is needed for full correction.

Rolando

-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 9:40 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Pointing and Error Correction turning off in APCC when parking at custom park position

Ray Gralak
 

I'm just a little confused as to where this should be used in ACP?

As the pointing & tracking correction turn off everytime the mount is parked,
the script would need to run after every unpark.
You would need to run it when unparking from the driver's custom park position. I can't tell you where that would be in ACP's script logic. You'll have to ask Bob Denny how/where to call the script if you want to do it in an automated way.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of David Trappett via Groups.Io
Sent: Saturday, February 15, 2020 3:39 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Pointing and Error Correction turning off in APCC when parking at custom park position

Thanks very much for this Ray,

I'm just a little confused as to where this should be used in ACP?

As the pointing & tracking correction turn off everytime the mount is parked, the script would need to run after every
unpark.

Regards,

DT


Re: Pointing and Error Correction turning off in APCC when parking at custom park position

David Trappett
 

Thanks very much for this Ray,

I'm just a little confused as to where this should be used in ACP?

As the pointing & tracking correction turn off everytime the mount is parked, the script would need to run after every unpark.

Regards,

DT


Re: Close up of M81 without CCDT67

Robert Chozick
 

Thanks for the suggestions.

On Feb 14, 2020, at 10:30 PM, Dale Ghent <daleg@elemental.org> wrote:


I wouldn't use tape. It's prone to turning out to be a mess, has a high chance of not being perfectly circular, and yea the adhesive could have an effect on the coating.

I would have a mask 3D printed and placed over the mirror, with it affixed to the inside wall of the OTA. A bunch of imagers I run with have started making these to mask out the mirror clips on their newtonians. If that's not doable, maybe work with a local sign maker who can accurately size and cleanly cut a mask from a rigid, thin material that does not shed particles. Should be easy if you just want to hide the edges.

On Feb 14, 2020, at 10:56 PM, Robert Chozick via Groups.Io <rchozick=aol.com@groups.io> wrote:

If I were to attempt to mask the edge what kind of tape can you use that wouldn’t harm the coatings?

Robert


On Feb 14, 2020, at 8:40 PM, Robert Chozick via Groups.Io <rchozick=aol.com@groups.io> wrote:
Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown.

I worked hard on my collimation and it seems to have paid off. I bought a focuser collimation ring and used a laser to collimate.

Robert


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@aol.com> via Groups.Io <chris1011=aol.com@groups.io> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick=aol.com@groups.io>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:

https://pbase.com/rchozick/image/170381415

I got M101 at 1600 but the seeing was worse and guiding not as good.

https://pbase.com/image/170399423

Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@aol.com> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it) :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick=aol.com@groups.io>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland. My last dark sky outing was my first use of this scope and camera. I am really confused on the whole image scale question. I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm. My scale is about 1.8 with my FSQ 106 - 530mm. If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale. Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294. Is oversampling bad? The .6 scale in my image sure looks ok. What about .4 or .3? I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over). Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC. The above reason is why. Each new CMOS camera that comes out still has really small pixels. How good would 2.5 micron pixels look on a 2500 mm scope?

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@aol.com> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick=aol.com@groups.io>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.

https://pbase.com/image/170419535

Robert Chozick
rchozick@aol.com




Robert Chozick
rchozick@aol.com




Robert Chozick
rchozick@aol.com





Re: Close up of M81 without CCDT67

Dale Ghent
 

I wouldn't use tape. It's prone to turning out to be a mess, has a high chance of not being perfectly circular, and yea the adhesive could have an effect on the coating.

I would have a mask 3D printed and placed over the mirror, with it affixed to the inside wall of the OTA. A bunch of imagers I run with have started making these to mask out the mirror clips on their newtonians. If that's not doable, maybe work with a local sign maker who can accurately size and cleanly cut a mask from a rigid, thin material that does not shed particles. Should be easy if you just want to hide the edges.

On Feb 14, 2020, at 10:56 PM, Robert Chozick via Groups.Io <rchozick=aol.com@groups.io> wrote:

If I were to attempt to mask the edge what kind of tape can you use that wouldn’t harm the coatings?

Robert


On Feb 14, 2020, at 8:40 PM, Robert Chozick via Groups.Io <rchozick=aol.com@groups.io> wrote:

Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown.

I worked hard on my collimation and it seems to have paid off. I bought a focuser collimation ring and used a laser to collimate.

Robert


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@aol.com> via Groups.Io <chris1011=aol.com@groups.io> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick=aol.com@groups.io>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:

https://pbase.com/rchozick/image/170381415

I got M101 at 1600 but the seeing was worse and guiding not as good.

https://pbase.com/image/170399423

Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@aol.com> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it) :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick=aol.com@groups.io>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland. My last dark sky outing was my first use of this scope and camera. I am really confused on the whole image scale question. I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm. My scale is about 1.8 with my FSQ 106 - 530mm. If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale. Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294. Is oversampling bad? The .6 scale in my image sure looks ok. What about .4 or .3? I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over). Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC. The above reason is why. Each new CMOS camera that comes out still has really small pixels. How good would 2.5 micron pixels look on a 2500 mm scope?

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@aol.com> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick=aol.com@groups.io>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.

https://pbase.com/image/170419535

Robert Chozick
rchozick@aol.com




Robert Chozick
rchozick@aol.com




Robert Chozick
rchozick@aol.com



Re: Close up of M81 without CCDT67

Robert Chozick
 

If I were to attempt to mask the edge what kind of tape can you use that wouldn’t harm the coatings?

Robert 


On Feb 14, 2020, at 8:40 PM, Robert Chozick via Groups.Io <rchozick@...> wrote:

Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Close up of M81 without CCDT67

Robert Chozick
 

Can you start making some smaller RC’s😀Thanks for the suggestion. One of the problems is how sensitive the CMOS cameras are. It is very easy to blow out stars. With my FSQ at f/5 I can’t shoot over 2 1/2 -3 minutes before bright stars are blown. 

I worked hard on my collimation and it seems to have paid off.  I bought a focuser collimation ring and used a laser to collimate.   

Robert 


On Feb 14, 2020, at 4:56 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: Close up of M81 without CCDT67

Roland Christen
 

I like the resolution on that Running Man image. Very nice.

Try masking down the outer 1/8 inch of the mirror, see if that reduces the spray of light around the brightest stars. If that works, think about adding a disc in front of the mirror with a diameter perhaps 1/4 inch smaller than the mirror.

I have seen this on all Russian RCs (RC Optical scopes) where a disc of slightly smaller aperture really helped. Most of the RC mirrors from Lomo had turned edge and were only spec'd to 95% of the full aperture. The very outer part produced a heavy spray of light around bright stars.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:47 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




Re: 1200GTO worm gear thrust washer?

Roland Christen
 

Tighten it hand tight (do not apply too much pressure, we use between 10 and 15 inch-Lb.). Then add a drop of superglue on the outside of the threads.
If you ever need to loosen it for any reason, it will be easy to unscrew after applying a bit of acetone to the glue spot.

Rolando



-----Original Message-----
From: Mike Shade <mshade@q.com>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 3:32 pm
Subject: [ap-gto] 1200GTO worm gear thrust washer?

The flat washer, the one with two holes on it at the end of the worm shaft (under the little screw on cover) continues to loosen up causing some degree of backlash.  It has done it for both RA and DEC.  Any ideas how to tighten this properly and prevent it from doing this in the future?
 
Mike J. Shade: mshade@q.com
Mike J. Shade Photography:
 
In War: Resolution
In Defeat: Defiance
In Victory: Magnanimity
In Peace: Goodwill
Sir Winston Churchill
Already, in the gathering dusk, a few of the stars are turning on their lights.
Vega, the brightest one, is now dropping towards the west.  Can it be half
a year since I watched her April rising in the east?  Low in the southwest
Antares blinks a sad farwell to fall...
Leslie Peltier, Starlight Nights
 
International Dark Sky Association: www.darksky.org
 
 


Re: Close up of M81 without CCDT67

Stuart <stuart.j.heggie@...>
 

Robert, these are both super shots but the Running Man is my favorite for sure.


On Fri, 14 Feb 2020 at 16:47, Robert Chozick via Groups.Io <rchozick=aol.com@groups.io> wrote:
So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.

https://pbase.com/image/170419535

Robert Chozick
rchozick@...




Robert Chozick
rchozick@...




Robert Chozick




--

Stuart
http://www.astrofoto.ca/stuartheggie/


Re: Close up of M81 without CCDT67

Robert Chozick
 

So, would you say the new advantages of the small pixel CMOS cameras is that they bring high sensitivity to small pixels?

I also got a shot of the Running Man with the 1600mm setup:


I got M101 at 1600 but the seeing was worse and guiding not as good. 


Robert



On Feb 14, 2020, at 3:10 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

You are running 0.6 arc sec per pixel, which to me is not oversampling for high resolution imaging. In fact, for galaxies i prefer 0.3 to 0.4 arc sec per pixel which really brings out fine detail. My 17"F8 astrograph and the QSI 683 has such pixel scale and really does a superb job on small faint galaxies, even here in Northern Illinois. You have to have good tracking, of course, and on the best nights I can get below 0.15 arc sec RMS with the 1600 encoder mount.

I see a lot of images that are way undersampled (3 to 4 arc sec per pixel) with poor guiding that produces thick stars and very little resolution. To me these images resemble Brownie camera snapshots versus images taken with an 8x10 view camera. (shows my age, doesn't it)  :^))

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 2:14 pm
Subject: Re: [ap-gto] Close up of M81 without CCDT67

Thanks Roland.  My last dark sky outing was my first use of this scope and camera.   I am really confused on the whole image scale question.  I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm.   My scale is about 1.8 with my FSQ 106 - 530mm.  If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale.  Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294.  Is oversampling bad?  The .6 scale in my image sure looks ok.    What about .4 or .3?  I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over).  Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC.  The above reason is why.   Each new CMOS camera that comes out still has really small pixels.   How good would 2.5 micron pixels look on a 2500 mm scope?  

Robert

On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <chris1011@...> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.

Rolando



-----Original Message-----
From: Robert Chozick via Groups.Io <rchozick@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.


Robert Chozick




Robert Chozick




Robert Chozick




1200GTO worm gear thrust washer?

Mike Shade
 

The flat washer, the one with two holes on it at the end of the worm shaft (under the little screw on cover) continues to loosen up causing some degree of backlash.  It has done it for both RA and DEC.  Any ideas how to tighten this properly and prevent it from doing this in the future?

 

Mike J. Shade: mshade@q.com

Mike J. Shade Photography:

mshadephotography.com

 

In War: Resolution

In Defeat: Defiance

In Victory: Magnanimity

In Peace: Goodwill

Sir Winston Churchill

Already, in the gathering dusk, a few of the stars are turning on their lights.

Vega, the brightest one, is now dropping towards the west.  Can it be half

a year since I watched her April rising in the east?  Low in the southwest

Antares blinks a sad farwell to fall...

Leslie Peltier, Starlight Nights

 

International Dark Sky Association: www.darksky.org

 

 

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