Date   

Re: Exposure comparisons with CCD cameras

Michael Hambrick <mike.hambrick@...>
 

Very good comparison Roland Thanks

I have read that the signal to noise ratio is higher for long exposures, but is there a limit to what can be accomplished with long exposures ? What happens to the stars and objects that reach the saturation limit ? Is it better to stack shorter, non-saturated exposures ?


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...


Re: APCC Pro Modeling and side by side setup.

Keith Olsen
 

OK Thank you Rolando.  I'm new to the Pro version, so if I create two models is there a way to switch between the models for the scope that I would be using?

Keith


Re: APCC Pro Modeling and side by side setup.

Roland Christen
 

If both scope show little or no differential flexure, I would make one model for the longer one. However, if they start to diverge after a period of tracking time, and you are using only one at a time, then two models would be needed for absolute est results.

Rolando



-----Original Message-----
From: Keith <keitholsen@...>
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 2:29 pm
Subject: [ap-gto] APCC Pro Modeling and side by side setup.

For modleing with a a side by side imaging setup will I need to make a seperate model for each telescope? One side is mid range(910 mm) and the other side is wide field.

Keith


APCC Pro Modeling and side by side setup.

Keith Olsen
 

For modleing with a a side by side imaging setup will I need to make a seperate model for each telescope? One side is mid range(910 mm) and the other side is wide field.

Keith


Re: Exposure comparisons with CCD cameras

Roland Christen
 

Your questions are always welcome in this group. They need to be specific so that people who have done something similar can comment.

When it comes to observatories, I only know roll-off roofs and their peculiarities. I have two of them now, one here in light pollution-city and one in a very dark site in Hawaii. We also have a remote observatory in Chile at 7000ft in the Andes mountains at Las Campanas. each one has their own issues and strengths, but with the right equipment, they can all do a super job.

As far as Domed observatories, I have only limited experience. They don't work for me because I like to be with my scope when imaging and most domes are too crowded. I also don't like the fact that the instruments (and observer) have to exit their stored heat out thru the dome slit, the same opening thru which the scope has to acquire images.

Rolando



-----Original Message-----
From: Stone, Jack G <jack.g.stone@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Cc: Stone, Jack G <jack.g.stone@...>
Sent: Tue, Aug 18, 2020 2:17 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Sorry – I did not mean that in a negative manner.
I’m just so impressed when someone has successfully tackled the LP challenge.
 
I worry that my questions would seem really dumb questions that I should know – hence my reluctance.
I did post a question regarding Observatory planning and available software.
But I never got a response
 
Story is that I purchased a spanking new AP1100 GTO4 – and the observatory I have seems like a very tight fit.  So a year later it sits unused.
So how can one make an assessment without models or ???  I tried simple geometry, but there is always something amiss in the 3D element.
Like the dome drive track and motor mount etc…..  The motor is rather ancient still works, and dialed in steady incremental rotations using my servo tester.
 
So now I’m thinking of selling the current one, but which one will fit, support my 14” Edge with HS etc… and not stand out like the statue of liberty.
Rather low profile as well.
Any thoughts or considerations would be welcomed.
As for the LED lights – Lenhance Extreme – but that would limit my targets – Any other thoughts?
 
I have tons of questions!!!
Also I’ve search on CN as well, and found a couple of others who restored their Boyd Observatories.
 
Cheers,
 
Jack ~
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 11:32 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
 
Bring your questions up here in the user group. That's what we are for, not just for analyzing problems.
 
Rolando
 
 
 
-----Original Message-----
From: Stone, Jack G <jack.g.stone@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Cc: Jack Stone <mediwheel_js@...>
Sent: Tue, Aug 18, 2020 1:29 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
Rolando – You give me hope! I will ping you later, I’ve been somewhat apprehensive for the past few years.
Finally the city replaced the MV with LED – guess what they must be 1million lumens – enough to bring daylight to my backyard.
Tips and tricks if you allow me to bug you.
 
Jack ~
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 11:22 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
 
My "backyard' (AP observatory) is in a heavily light polluted area in an industrial park with large malls, gas stations, fast food joints etc, all competing for brightest lights in the neighborhood. The narrowband filter blocks a lot of that sky light, otherwise i would get a white frame with a luminance filter in a 1 hour exposure.
 
Rolando
 
 
 
-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Aug 18, 2020 1:09 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
Hi Rolando,
   
   I think you know more about this than I do. But here's what I think:
 
   In order for stacking to actually show the faint details, it has to be a little above the noise floor and then stacking (or averaging) lowers the noise floor so that the coherent signal pops up. If there are no photons that were caught above the noise floor then averaging will do no good: zero == zero no matter how you average.
 
  That's why your long exposure caught enough photons above noise floor from the faint bits to show up. Your backyard must be much darker than mine, because as you increase the exposure time, noise also goes up as well, so at some point the noise is going to dominate  and increasing the exposure time doesn't buy you anything.
 
cytan
 
 
 
On Tuesday, August 18, 2020, 01:03:28 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:
 
 
 
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.
Yes, higher read noise of course, but interestingly the amount of faint detail is also higher in the 1 hour exposure. Perhaps the detail is there in the stacked image, but buried in read noise.
 
I don't know how this would relate to CMOS cameras, but CCDs is a different animal. I'm going to try adding several 1 hour exposures if skies permit and see how much faint Ha I can dig out of my light polluted skies.
 
Rolando
 
 
-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>; main@ap-ug.groups.io <main@ap-ug.groups.io>
Sent: Tue, Aug 18, 2020 12:59 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
Hi Rolando,
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.
 
cytan
 
On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:
 
 
Hello Astronuts,
 
Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.
 
Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:
 
 
As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.
 
Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:
 


Re: Exposure comparisons with CCD cameras

Stone, Jack G
 

Sorry – I did not mean that in a negative manner.

I’m just so impressed when someone has successfully tackled the LP challenge.

 

I worry that my questions would seem really dumb questions that I should know – hence my reluctance.

I did post a question regarding Observatory planning and available software.

But I never got a response

 

Story is that I purchased a spanking new AP1100 GTO4 – and the observatory I have seems like a very tight fit.  So a year later it sits unused.

So how can one make an assessment without models or ???  I tried simple geometry, but there is always something amiss in the 3D element.

Like the dome drive track and motor mount etc…..  The motor is rather ancient still works, and dialed in steady incremental rotations using my servo tester.

 

So now I’m thinking of selling the current one, but which one will fit, support my 14” Edge with HS etc… and not stand out like the statue of liberty.

Rather low profile as well.

Any thoughts or considerations would be welcomed.

As for the LED lights – Lenhance Extreme – but that would limit my targets – Any other thoughts?

 

I have tons of questions!!!

Also I’ve search on CN as well, and found a couple of others who restored their Boyd Observatories.

 

Cheers,

 

Jack ~

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 11:32 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

 

Bring your questions up here in the user group. That's what we are for, not just for analyzing problems.

 

Rolando

 

 

 

-----Original Message-----
From: Stone, Jack G <jack.g.stone@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Cc: Jack Stone <mediwheel_js@...>
Sent: Tue, Aug 18, 2020 1:29 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Rolando – You give me hope! I will ping you later, I’ve been somewhat apprehensive for the past few years.

Finally the city replaced the MV with LED – guess what they must be 1million lumens – enough to bring daylight to my backyard.

Tips and tricks if you allow me to bug you.

 

Jack ~

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 11:22 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

 

My "backyard' (AP observatory) is in a heavily light polluted area in an industrial park with large malls, gas stations, fast food joints etc, all competing for brightest lights in the neighborhood. The narrowband filter blocks a lot of that sky light, otherwise i would get a white frame with a luminance filter in a 1 hour exposure.

 

Rolando

 

 

 

-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Aug 18, 2020 1:09 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,

   

   I think you know more about this than I do. But here's what I think:

 

   In order for stacking to actually show the faint details, it has to be a little above the noise floor and then stacking (or averaging) lowers the noise floor so that the coherent signal pops up. If there are no photons that were caught above the noise floor then averaging will do no good: zero == zero no matter how you average.

 

  That's why your long exposure caught enough photons above noise floor from the faint bits to show up. Your backyard must be much darker than mine, because as you increase the exposure time, noise also goes up as well, so at some point the noise is going to dominate  and increasing the exposure time doesn't buy you anything.

 

cytan

 

 

 

On Tuesday, August 18, 2020, 01:03:28 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

 

 

 

 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

Yes, higher read noise of course, but interestingly the amount of faint detail is also higher in the 1 hour exposure. Perhaps the detail is there in the stacked image, but buried in read noise.

 

I don't know how this would relate to CMOS cameras, but CCDs is a different animal. I'm going to try adding several 1 hour exposures if skies permit and see how much faint Ha I can dig out of my light polluted skies.

 

Rolando

 

 

-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>; main@ap-ug.groups.io <main@ap-ug.groups.io>
Sent: Tue, Aug 18, 2020 12:59 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,

 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

 

cytan

 

On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:

 

 

Hello Astronuts,

 

Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.

 

Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:

 

 

As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.

 

Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:

 


APPM and color cameras #APCC

Dean Jacobsen
 

I have been thinking about picking up a color camera based on the APS-C size IMX571.  That would mean that I would need to do my SharpCap polar alignment and my APPM point mapping with a Bayer matrix camera.

Will the camera work OK with APPM and SharpCap?  Everything else would remain the same with APPM - images would be taken with SG Pro and Plate Solve 2.

--
Dean Jacobsen
http://astrophoto.net/wp/
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Re: Exposure comparisons with CCD cameras

Roland Christen
 

Bring your questions up here in the user group. That's what we are for, not just for analyzing problems.

Rolando



-----Original Message-----
From: Stone, Jack G <jack.g.stone@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Cc: Jack Stone <mediwheel_js@...>
Sent: Tue, Aug 18, 2020 1:29 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Rolando – You give me hope! I will ping you later, I’ve been somewhat apprehensive for the past few years.
Finally the city replaced the MV with LED – guess what they must be 1million lumens – enough to bring daylight to my backyard.
Tips and tricks if you allow me to bug you.
 
Jack ~
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 11:22 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
 
My "backyard' (AP observatory) is in a heavily light polluted area in an industrial park with large malls, gas stations, fast food joints etc, all competing for brightest lights in the neighborhood. The narrowband filter blocks a lot of that sky light, otherwise i would get a white frame with a luminance filter in a 1 hour exposure.
 
Rolando
 
 
 
-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Aug 18, 2020 1:09 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
Hi Rolando,
   
   I think you know more about this than I do. But here's what I think:
 
   In order for stacking to actually show the faint details, it has to be a little above the noise floor and then stacking (or averaging) lowers the noise floor so that the coherent signal pops up. If there are no photons that were caught above the noise floor then averaging will do no good: zero == zero no matter how you average.
 
  That's why your long exposure caught enough photons above noise floor from the faint bits to show up. Your backyard must be much darker than mine, because as you increase the exposure time, noise also goes up as well, so at some point the noise is going to dominate  and increasing the exposure time doesn't buy you anything.
 
cytan
 
 
 
On Tuesday, August 18, 2020, 01:03:28 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:
 
 
 
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.
Yes, higher read noise of course, but interestingly the amount of faint detail is also higher in the 1 hour exposure. Perhaps the detail is there in the stacked image, but buried in read noise.
 
I don't know how this would relate to CMOS cameras, but CCDs is a different animal. I'm going to try adding several 1 hour exposures if skies permit and see how much faint Ha I can dig out of my light polluted skies.
 
Rolando
 
 
-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>; main@ap-ug.groups.io <main@ap-ug.groups.io>
Sent: Tue, Aug 18, 2020 12:59 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras
Hi Rolando,
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.
 
cytan
 
On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:
 
 
Hello Astronuts,
 
Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.
 
Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:
 
 
As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.
 
Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:
 


Re: Exposure comparisons with CCD cameras

Stone, Jack G
 

Rolando – You give me hope! I will ping you later, I’ve been somewhat apprehensive for the past few years.

Finally the city replaced the MV with LED – guess what they must be 1million lumens – enough to bring daylight to my backyard.

Tips and tricks if you allow me to bug you.

 

Jack ~

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of uncarollo2 <chris1011@...> via groups.io
Sent: Tuesday, August 18, 2020 11:22 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

 

My "backyard' (AP observatory) is in a heavily light polluted area in an industrial park with large malls, gas stations, fast food joints etc, all competing for brightest lights in the neighborhood. The narrowband filter blocks a lot of that sky light, otherwise i would get a white frame with a luminance filter in a 1 hour exposure.

 

Rolando

 

 

 

-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Aug 18, 2020 1:09 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,

   

   I think you know more about this than I do. But here's what I think:

 

   In order for stacking to actually show the faint details, it has to be a little above the noise floor and then stacking (or averaging) lowers the noise floor so that the coherent signal pops up. If there are no photons that were caught above the noise floor then averaging will do no good: zero == zero no matter how you average.

 

  That's why your long exposure caught enough photons above noise floor from the faint bits to show up. Your backyard must be much darker than mine, because as you increase the exposure time, noise also goes up as well, so at some point the noise is going to dominate  and increasing the exposure time doesn't buy you anything.

 

cytan

 

 

 

On Tuesday, August 18, 2020, 01:03:28 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

 

 

 

 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

Yes, higher read noise of course, but interestingly the amount of faint detail is also higher in the 1 hour exposure. Perhaps the detail is there in the stacked image, but buried in read noise.

 

I don't know how this would relate to CMOS cameras, but CCDs is a different animal. I'm going to try adding several 1 hour exposures if skies permit and see how much faint Ha I can dig out of my light polluted skies.

 

Rolando

 

 

-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>; main@ap-ug.groups.io <main@ap-ug.groups.io>
Sent: Tue, Aug 18, 2020 12:59 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,

 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

 

cytan

 

On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:

 

 

Hello Astronuts,

 

Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.

 

Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:

 

 

As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.

 

Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:

 


Re: Exposure comparisons with CCD cameras

Roland Christen
 

My "backyard' (AP observatory) is in a heavily light polluted area in an industrial park with large malls, gas stations, fast food joints etc, all competing for brightest lights in the neighborhood. The narrowband filter blocks a lot of that sky light, otherwise i would get a white frame with a luminance filter in a 1 hour exposure.

Rolando



-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Aug 18, 2020 1:09 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,
   
   I think you know more about this than I do. But here's what I think:

   In order for stacking to actually show the faint details, it has to be a little above the noise floor and then stacking (or averaging) lowers the noise floor so that the coherent signal pops up. If there are no photons that were caught above the noise floor then averaging will do no good: zero == zero no matter how you average.

  That's why your long exposure caught enough photons above noise floor from the faint bits to show up. Your backyard must be much darker than mine, because as you increase the exposure time, noise also goes up as well, so at some point the noise is going to dominate  and increasing the exposure time doesn't buy you anything.

cytan



On Tuesday, August 18, 2020, 01:03:28 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:



 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.
Yes, higher read noise of course, but interestingly the amount of faint detail is also higher in the 1 hour exposure. Perhaps the detail is there in the stacked image, but buried in read noise.

I don't know how this would relate to CMOS cameras, but CCDs is a different animal. I'm going to try adding several 1 hour exposures if skies permit and see how much faint Ha I can dig out of my light polluted skies.

Rolando


-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>; main@ap-ug.groups.io <main@ap-ug.groups.io>
Sent: Tue, Aug 18, 2020 12:59 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

cytan

On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:


Hello Astronuts,

Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.

Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:

https://www.astrobin.com/916uf7/B/

As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.

Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:


Re: Exposure comparisons with CCD cameras

Cheng-Yang Tan
 

Hi Rolando,
   
   I think you know more about this than I do. But here's what I think:

   In order for stacking to actually show the faint details, it has to be a little above the noise floor and then stacking (or averaging) lowers the noise floor so that the coherent signal pops up. If there are no photons that were caught above the noise floor then averaging will do no good: zero == zero no matter how you average.

  That's why your long exposure caught enough photons above noise floor from the faint bits to show up. Your backyard must be much darker than mine, because as you increase the exposure time, noise also goes up as well, so at some point the noise is going to dominate  and increasing the exposure time doesn't buy you anything.

cytan



On Tuesday, August 18, 2020, 01:03:28 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:



 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.
Yes, higher read noise of course, but interestingly the amount of faint detail is also higher in the 1 hour exposure. Perhaps the detail is there in the stacked image, but buried in read noise.

I don't know how this would relate to CMOS cameras, but CCDs is a different animal. I'm going to try adding several 1 hour exposures if skies permit and see how much faint Ha I can dig out of my light polluted skies.

Rolando


-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>; main@ap-ug.groups.io <main@ap-ug.groups.io>
Sent: Tue, Aug 18, 2020 12:59 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

cytan

On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:


Hello Astronuts,

Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.

Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:

https://www.astrobin.com/916uf7/B/

As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.

Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:


Re: Exposure comparisons with CCD cameras

Roland Christen
 


 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.
Yes, higher read noise of course, but interestingly the amount of faint detail is also higher in the 1 hour exposure. Perhaps the detail is there in the stacked image, but buried in read noise.

I don't know how this would relate to CMOS cameras, but CCDs is a different animal. I'm going to try adding several 1 hour exposures if skies permit and see how much faint Ha I can dig out of my light polluted skies.

Rolando


-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>; main@ap-ug.groups.io <main@ap-ug.groups.io>
Sent: Tue, Aug 18, 2020 12:59 pm
Subject: Re: [ap-gto] Exposure comparisons with CCD cameras

Hi Rolando,
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

cytan

On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:


Hello Astronuts,

Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.

Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:

https://www.astrobin.com/916uf7/B/

As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.

Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:


Re: Exposure comparisons with CCD cameras

Cheng-Yang Tan
 

Hi Rolando,
 This is a very interesting result. It looks like the noise of the exposure is dominated by the read noise in your CCD camera.

cytan

On Tuesday, August 18, 2020, 12:51:43 PM CDT, uncarollo2 <chris1011@...> wrote:


Hello Astronuts,

Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.

Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:

https://www.astrobin.com/916uf7/B/

As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.

Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:


Re: AP1100 GTO will not slew to target

Roland Christen
 

Sure, why not.

Roland



-----Original Message-----
To: main@ap-gto.groups.io
Sent: Tue, Aug 18, 2020 12:54 pm
Subject: Re: [ap-gto] AP1100 GTO will not slew to target

Thank you all! You,ve been very helpful.
One last question. If all else fails is it possible to plug in my older CP2 from my older AP900 in place of the CP4 just to see if
would eliminate the CP as being the problem?
John


Re: AP1100 GTO will not slew to target

hallj1531@...
 

Thank you all! You,ve been very helpful.
One last question. If all else fails is it possible to plug in my older CP2 from my older AP900 in place of the CP4 just to see if
would eliminate the CP as being the problem?
John


Exposure comparisons with CCD cameras

Roland Christen
 

Hello Astronuts,

Last night was a good night to try some experiments with the Mach2 mount and my 160 EDF refractor. I have been shooting the Veil nebula for the last couple of nights, normally using 10 minute subs and stacking them. I have not been guiding, but using modeling of the path to get sharp round stars.

Last night i did one exposure of 60 minutes and 6 exposures of 10 minutes each (60 minute stack). I wanted to see how the faint detail and noise levels compare. It turns out that the single 60 minute shot has much lower noise and shows more fainter details than the 60 minute stacked image. In fact, it took 120 minutes of stacked images to equal the single 60 minute one. You can see the result here:

https://www.astrobin.com/916uf7/B/

As noted, the images were stretched to bring up the faintest detail and to show the noise levels. It appears to me that longer exposures for narrowband produce better results faster. There are two drawbacks. The image can be ruined by satellites or airplane trails. A 1 hour exposure requires some guiding.

Both images had the model running in the background, which was good for round stars in a 10 minute time interval. However for the 1 hour exposure I wanted to make sure the stars would be round and sharp, so I set up my Lodestar off-axis guider. The guider was set to take a 2 sec exposure every 10 seconds to nudge the two axes. The image below shows how well the mount guides when it is also being modeled:


Re: AP1100 GTO will not slew to target

Howard Hedlund
 

Hi John,

If you don't find the solution from Ray's suggestion, please give me a call to discuss.  My AP Tech Support cell # is 815-315-seven zero one five.


Re: AP1100 GTO will not slew to target

Ray Gralak
 

Hi John,

In case you didn't see it, I sent you a private email with something you should try.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
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 hallj1531@gmail.com
Sent: Tuesday, August 18, 2020 9:55 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] AP1100 GTO will not slew to target

Thank You! I will give it a try with the keypad and go from there.
John


Re: AP1100 GTO will not slew to target

hallj1531@...
 

Thank You! I will give it a try with the keypad and go from there.
John


Re: AP1100 GTO will not slew to target

Mike Dodd
 

On 8/18/2020 12:15 PM, uncarollo2 <chris1011@aol.com> via groups.io wrote:
If no keypad is available,
use the ASCOM driver to move the mount around via the buttons at various
speeds from 1x, 12x, 64x, 600x 900x and 1200x button speeds. If that
works, then the mount is ok. The problem would be elsewhere in your
other software setup.
That's exactly what I was going to say. If the ASCOM driver buttons work OK at 600X or slower, set the slew speed in the driver to the same speed, then try using the AP Jog Utility to move the mount.

The Jog utility is an application that USES the ASCOM driver, so if the mount works with it, but not with other software, you know the mount is OK.

The Jog utility lets you specify the distance to move, so start at 1 degree and work upward. See if the mount operates correctly. If so, then, as Roland said, something is going on with other software.

--- Mike

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