Date   

Re: Elephant Trunk, AP1100AE as a sleep aide

Bill Long
 

I only crop stacking artifacts and I prefer my scopes can well correct the IMX455. All speed makes a difference, and like I said that Takahashi reducer cannot correct the big chip. I'm not actually sure the CRS250 can cover the IMX455 as it's advertised corrected field is 40mm without the reducer. So personally I'd pass on a $9k f10/f7.2 scope limited to APSC chips.

To me the target customers are those with large sensors that would love a 10" scope in the 1600mm range, with excellent optics, that has a 60mm+ corrected field of pretty stars. There are no other options available in that combination. 

As for the size of the market, this is an AP scope being suggested. It'll sell out easily as soon as the list goes up. 😊


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of weems@... <weems@...>
Sent: Sunday, September 25, 2022 7:19 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 

As I said, undoubtedly a case can be made. But I’m trying to think in marketing terms about the customer base.

If it’s in the $22,000 range that the current 10” f14.5 is, many potential customers who are looking to step up for higher quality optics from something like an SCT, will ask themselves questions like, “how often do I really shoot objects that I don’t crop?” Or, “will a third of a stop in f ratio really matter?” Or, “do pretty spikes on bright stars, like the ones in big observatory photos, really bother me that much?” Or, “can I live with having to refocus a few times in a night?” One other advantage of a Mak, the small secondary obstruction, may also be lost at f6.3. So it may not be as attractive for planet imagers.

So who are the customers? How big is the market? Will it be just people who currently image with extremely high quality refractors at around f6.3 and want the same thing with more aperture, but don’t mind a larger obstruction? Maybe there are enough of those to buy a production run that will turn a profit after the development costs are taken out. Or maybe there is a larger base. But it’s still likely to be a small enough market to warrant a careful study before committing to production level development. 

Chip


Re: Elephant Trunk, AP1100AE as a sleep aide

weems@...
 

As I said, undoubtedly a case can be made. But I’m trying to think in marketing terms about the customer base.

If it’s in the $22,000 range that the current 10” f14.5 is, many potential customers who are looking to step up for higher quality optics from something like an SCT, will ask themselves questions like, “how often do I really shoot objects that I don’t crop?” Or, “will a third of a stop in f ratio really matter?” Or, “do pretty spikes on bright stars, like the ones in big observatory photos, really bother me that much?” Or, “can I live with having to refocus a few times in a night?” One other advantage of a Mak, the small secondary obstruction, may also be lost at f6.3. So it may not be as attractive for planet imagers.

So who are the customers? How big is the market? Will it be just people who currently image with extremely high quality refractors at around f6.3 and want the same thing with more aperture, but don’t mind a larger obstruction? Maybe there are enough of those to buy a production run that will turn a profit after the development costs are taken out. Or maybe there is a larger base. But it’s still likely to be a small enough market to warrant a careful study before committing to production level development. 

Chip


Re: ACPP problem Virtual Port #APCC

robert.l.wahlstrom@...
 

I tried virtual com ports /  REST  and have been trying to test for a few days now...


I test more in  astro-physic mail.. 


Re: Unwanted AP1600 Mount Passenger

W Hilmo
 

When I lived in the Seattle area, I kept my AP1600 set up in the back yard with a TG365 cover.  One day, I uncovered the mount after a significant period of no clear nights.  Some enterprising critter had completely filled the inside of the mount with maple seeds.  And I mean completely.  It was packed solid, from the counterweight shaft adapter, to the underside of the declination top plate.

I got lucky in that the critter didn't move in.  It actually took just a few minutes to clean it out, since the seeds were dry and mostly just fell out when I removed the counterweight shaft adapter and separated the halves of the mount.

On 9/24/22 18:19, Patrick Sparkman via groups.io wrote:

A couple of weeks ago, I dismantled my AP1600 that is normally on my back patio.  I use a cover, but we were supposed to get some tropical storm force winds (they never got that high) so I dismantled the scope to bring it inside.  When I unscrewed the counterweight cover it was holding a small mouse nest made of mulch from the yard.  Then when I took off the top Dec plate, the passenger was still in the mount!  The only place where it could have entered the mount was where the through-mount power/usb cables enter the back of the mount.

So, I designed and 3D printed a couple of plates to better seal against the cables.  Thankfully I found this before it started chewing wires or worse!

Attachments:



Re: Elephant Trunk, AP1100AE as a sleep aide

Bill Long
 

The Mak Cass doesn't have a spider, is a faster focal ratio, and has a much larger corrected field. That reducer, which I have for my iDK, cannot correct a full frame CMOS. Takahashi doesn't call out what mirror type they use, so if it's not quartz it's behind in that as well.

 So I'd call the Mak a winner all around.



From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of weems@... <weems@...>
Sent: Saturday, September 24, 2022 9:56 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 
A 10” MCT at f6.3 might be too close to a Takahashi Mewlon 250 with their f7.3 fat field reducer, which are currently listed for around $8800. It would need to make  a clear competitive distinction. That’s undoubtedly possible, but just at an abstract level, they could sound pretty similar.

Chip


Re: Unwanted AP1600 Mount Passenger

fernandorivera3
 

Wouldn't hurt having some furry felines in close proximity to the mount 🤔

Fernando


Electronic Focuser

Chanan Greenberg
 

Hi All,

Running an old AP 5" Starfire F/6 on an AP900.

Does anyone here use this focuser 27FOC3E-FT (https://www.astro-physics.com/27foc3e-ft) and can you recommend an electronic focuser with temp control / compensation that you know is compatible?

Thanks
Chanan


Re: Elephant Trunk, AP1100AE as a sleep aide

weems@...
 

A 10” MCT at f6.3 might be too close to a Takahashi Mewlon 250 with their f7.3 fat field reducer, which are currently listed for around $8800. It would need to make  a clear competitive distinction. That’s undoubtedly possible, but just at an abstract level, they could sound pretty similar.

Chip


Re: custom hook to hang the keypad

M Hambrick
 

Good idea about the carabiner Tony.

I am still using the lanyard that came with my mount to attach to the sliding hook.

Mike


Re: Unwanted AP1600 Mount Passenger

M Hambrick
 

None of us are immune to unwanted visitors. I remember Roland posting a couple of pictures a year or two ago showing where the mice got to the wires.

Mike


Re: Unwanted AP1600 Mount Passenger

Howard Ritter
 

Hi, Patrick—

Sounds like a mighty close squeak! That could have turned into a real tail of woe. Someone needs to check a couple months from now whether one of the Mice Galaxies has escaped...

I keep my 1600 on my back patio too. I imagine there might be a few more of us, and of course even those with backyard observatories can’t be sure of being rodent-free.

Have you considered turning your 3D printer into a cottage industry?

—howard

On Sep 24, 2022, at 9:19 PM, Patrick Sparkman via groups.io <psparkman@...> wrote:

A couple of weeks ago, I dismantled my AP1600 that is normally on my back patio.  I use a cover, but we were supposed to get some tropical storm force winds (they never got that high) so I dismantled the scope to bring it inside.  When I unscrewed the counterweight cover it was holding a small mouse nest made of mulch from the yard.  Then when I took off the top Dec plate, the passenger was still in the mount!  The only place where it could have entered the mount was where the through-mount power/usb cables enter the back of the mount.

So, I designed and 3D printed a couple of plates to better seal against the cables.  Thankfully I found this before it started chewing wires or worse!

<image.jpeg><IMG_1280.jpg><IMG_1284.jpg>


Unwanted AP1600 Mount Passenger

Patrick Sparkman
 

A couple of weeks ago, I dismantled my AP1600 that is normally on my back patio.  I use a cover, but we were supposed to get some tropical storm force winds (they never got that high) so I dismantled the scope to bring it inside.  When I unscrewed the counterweight cover it was holding a small mouse nest made of mulch from the yard.  Then when I took off the top Dec plate, the passenger was still in the mount!  The only place where it could have entered the mount was where the through-mount power/usb cables enter the back of the mount.

So, I designed and 3D printed a couple of plates to better seal against the cables.  Thankfully I found this before it started chewing wires or worse!


Re: custom hook to hang the keypad

Joe Zeglinski
 

Great idea, Tony.
 
    We should also warn AP keypad-owners that the actual “sliding hook” on the keypad is “extremely”  thin, fragile, and brittle, so it can easily snap while trying to hang the keypad, unless a “Carabiner Hook”  is used – as you did.
 
    The AP sliding hook should have been made of a flexible nylon, or stainless steel.
 
    I snapped mine while trying to align it in the dark, on a  tripod’s hanger like yours.  Just a slight twist, and it snapped.  Then I had to epoxy a plastic support backing onto the broken keypad’s hook, to give it extra strength in order to prevent a repeat disaster.
Otherwise, the huge keypad and its coiled cable would then become a “coat-pocket” item, for the tethered observer :-(
 
  Your Carabiner provides the needed flexibility, to prevent such a  likely breakage.
 
Joe Z.
 
From: Harley Davidson
Sent: Saturday, August 13, 2022 8:48 PM
To: main@ap-gto.groups.io ; main@ap-ug.groups.io
Subject: [ap-gto] custom hook to hang the keypad
 
https://www.youtube.com/watch?v=hLdr6nAlcQw

I made a custom "hook" to hang the keypad from that uses one of the 1/4"/20 holes in the Mach2 mount. It can be scaled to any mount though. And it require no tools.

tony



Re: Elephant Trunk, AP1100AE as a sleep aide

Bill Long
 

This is a well thought out design. Maybe someday we'll get the chance to buy one. 😊



From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Roland Christen via groups.io <chris1011@...>
Sent: Saturday, September 24, 2022 8:48 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 
The main thermal effects of the 10" Mak are not so much focus shift but getting the optics to shed heat to eliminate tube currents. My design is a closed tube and consists of a front corrector lens, a secondary mirror assembly and a primary mirror in the rear. The front corrector sheds heat very fast because it is aimed at the dark sky so it radiates heat into the dark void. The mirror is insulated from that because it has an aluminum coating, so it cannot radiate heat the same way. Therefore we make the mirror quite thin and lightweight, plus the rear has removable louvers to allow the mirror's heat to escape. The main baffle is also designed to prevent warm air from rising inside the tube, so that prevents heat plumes from forming during cooldown.

An open tube truss design has some advantages when it comes to controlling tube currents, but there are a number of disadvantages too. Your mirror coatings are exposed to the air and can get atmospheric schmutz buildup. My 17" open tube truss has a very dirty mirror after a few years of operation in my observatory. Loss of contrast is the main result. I hate to clean it because aluminum coatings are somewhat fragile and cleaning can cause micro-scratches and sleeks. In a closed tube design the mirrors will stay pristine and only the front surface of the corrector needs to be cleaned - and those coatings are very robust and will not scratch with careful cleaning.

Roland

-----Original Message-----
From: Ram <ramviswanathan@...>
To: main@ap-gto.groups.io
Sent: Fri, Sep 23, 2022 8:08 pm
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

Is it possible to design a system that is perfectly thermo-compensated (within a 15F temp swing)? 

I have one of Yuri's scopes (TEC ADL300) that uses a combination of titanium truss tubes and aluminum spider that extends out in front of the truss.  So when the temperature drops, the titanium shrinks but the aluminum shrinks even more. 
That is compensated by the shrinkage of the aluminum extension tubes in the back in the opposite direction. I thought that design was quite clever. 

This way you focus once in the beginning of the night and you're done!


--
Roland Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

Bill Long
 


Awesome! Sounds great.


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Roland Christen via groups.io <chris1011@...>
Sent: Saturday, September 24, 2022 8:32 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 
No cooling fans - they are not needed. The mirror is light weight and fairly thin, so it cools down quickly. The back can be fully opened during cool-down. I have not seen any thermal issues.

Roland


-----Original Message-----
From: Bill Long <bill@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Fri, Sep 23, 2022 8:04 pm
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

I forgot to ask, does this Mak Cass have cooling fans on the rear blowing outward?

From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Bill Long <bill@...>
Sent: Friday, September 23, 2022 5:47 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 
My AGO Optical 12.5" iDK uses Quartz optics and a truss system, and I rarely need to refocus it after the system has stabilized for the night. I have a 14" CDK that has yet to be unboxed and is sitting at my future observatory site, that also uses quartz optics, and I would imagine the experience will be the same.

The 10" Mak Cass f6.3 would definitely be welcomed, IMO. That is in the portable range for long focal length optics, which I would not call the 12.5 or 14" scopes portable by any means. Now, I don't know how much the scope weighs, but I would imagine it would not be too heavy. Maybe around 25 lbs? Combined with the permanently aligned optics, I would love to have that for a trip with the Mach 2 to a dark site.


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Roland Christen via groups.io <chris1011@...>
Sent: Friday, September 23, 2022 5:10 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 

It doesnt appear that quartz optics and carbon fiber actually eliminate the need for autofocus
It may not, but it reduces the need for re-focusing from every 2 degrees F to around every 15 degrees F. In the summer i can leave the focus alone for pretty much all night. When a cold front moves thru we can sometimes get 30 degree temp shift in 3 hours time, which does require some focus touchup. In a Cassegrain, a slight shift of the corrector to mirror distance is amplified by the secondary amplification factor. In an SCT it is a factor of 5x. So aluminum tubes that shrink by 0.1mm from warm to cold will cause an image shift or 0.5mm. In my carbon fiber design there is no distance change and the amplification factor is only around 2.2x. The small amount of aluminum in the rear to the camera makes almost no difference. I've studied my design extensively in ATMOS and the shift is very small for a 15 degree F drop.

Roland


-----Original Message-----
From: Ram <ramviswanathan@...>
To: main@ap-gto.groups.io
Sent: Fri, Sep 23, 2022 6:37 pm
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

>>The main design parameters are fast focal ratio compared to an SCT, quartz mirror and carbon fiber tube for focus stability. I'm not sure if the latter two would be appreciated by imagers since people use focus routines to get around focus shift with temperature. The moment you add quartz optics and carbon fiber, you are adding several thousand to the retail price. Adding an Optec focuser adds another couple thou. So, is it worth it?

It doesnt appear that quartz optics and carbon fiber actually eliminate the need for autofocus -- you will have aluminum in your image train anyway (camera, extension tubes etc.) So the goal of thermo-compensation might be better than the goal of zero expansion. 
You still need focusers and focus routines, IMHO. Unless I am missing something.

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

Ram
 

Makes complete sense. Thanks.


Re: Elephant Trunk, AP1100AE as a sleep aide

Roland Christen
 

The main thermal effects of the 10" Mak are not so much focus shift but getting the optics to shed heat to eliminate tube currents. My design is a closed tube and consists of a front corrector lens, a secondary mirror assembly and a primary mirror in the rear. The front corrector sheds heat very fast because it is aimed at the dark sky so it radiates heat into the dark void. The mirror is insulated from that because it has an aluminum coating, so it cannot radiate heat the same way. Therefore we make the mirror quite thin and lightweight, plus the rear has removable louvers to allow the mirror's heat to escape. The main baffle is also designed to prevent warm air from rising inside the tube, so that prevents heat plumes from forming during cooldown.

An open tube truss design has some advantages when it comes to controlling tube currents, but there are a number of disadvantages too. Your mirror coatings are exposed to the air and can get atmospheric schmutz buildup. My 17" open tube truss has a very dirty mirror after a few years of operation in my observatory. Loss of contrast is the main result. I hate to clean it because aluminum coatings are somewhat fragile and cleaning can cause micro-scratches and sleeks. In a closed tube design the mirrors will stay pristine and only the front surface of the corrector needs to be cleaned - and those coatings are very robust and will not scratch with careful cleaning.

Roland

-----Original Message-----
From: Ram <ramviswanathan@...>
To: main@ap-gto.groups.io
Sent: Fri, Sep 23, 2022 8:08 pm
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

Is it possible to design a system that is perfectly thermo-compensated (within a 15F temp swing)? 

I have one of Yuri's scopes (TEC ADL300) that uses a combination of titanium truss tubes and aluminum spider that extends out in front of the truss.  So when the temperature drops, the titanium shrinks but the aluminum shrinks even more. 
That is compensated by the shrinkage of the aluminum extension tubes in the back in the opposite direction. I thought that design was quite clever. 

This way you focus once in the beginning of the night and you're done!


--
Roland Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

Roland Christen
 

No cooling fans - they are not needed. The mirror is light weight and fairly thin, so it cools down quickly. The back can be fully opened during cool-down. I have not seen any thermal issues.

Roland


-----Original Message-----
From: Bill Long <bill@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Fri, Sep 23, 2022 8:04 pm
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

I forgot to ask, does this Mak Cass have cooling fans on the rear blowing outward?

From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Bill Long <bill@...>
Sent: Friday, September 23, 2022 5:47 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 
My AGO Optical 12.5" iDK uses Quartz optics and a truss system, and I rarely need to refocus it after the system has stabilized for the night. I have a 14" CDK that has yet to be unboxed and is sitting at my future observatory site, that also uses quartz optics, and I would imagine the experience will be the same.

The 10" Mak Cass f6.3 would definitely be welcomed, IMO. That is in the portable range for long focal length optics, which I would not call the 12.5 or 14" scopes portable by any means. Now, I don't know how much the scope weighs, but I would imagine it would not be too heavy. Maybe around 25 lbs? Combined with the permanently aligned optics, I would love to have that for a trip with the Mach 2 to a dark site.


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Roland Christen via groups.io <chris1011@...>
Sent: Friday, September 23, 2022 5:10 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 

It doesnt appear that quartz optics and carbon fiber actually eliminate the need for autofocus
It may not, but it reduces the need for re-focusing from every 2 degrees F to around every 15 degrees F. In the summer i can leave the focus alone for pretty much all night. When a cold front moves thru we can sometimes get 30 degree temp shift in 3 hours time, which does require some focus touchup. In a Cassegrain, a slight shift of the corrector to mirror distance is amplified by the secondary amplification factor. In an SCT it is a factor of 5x. So aluminum tubes that shrink by 0.1mm from warm to cold will cause an image shift or 0.5mm. In my carbon fiber design there is no distance change and the amplification factor is only around 2.2x. The small amount of aluminum in the rear to the camera makes almost no difference. I've studied my design extensively in ATMOS and the shift is very small for a 15 degree F drop.

Roland


-----Original Message-----
From: Ram <ramviswanathan@...>
To: main@ap-gto.groups.io
Sent: Fri, Sep 23, 2022 6:37 pm
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

>>The main design parameters are fast focal ratio compared to an SCT, quartz mirror and carbon fiber tube for focus stability. I'm not sure if the latter two would be appreciated by imagers since people use focus routines to get around focus shift with temperature. The moment you add quartz optics and carbon fiber, you are adding several thousand to the retail price. Adding an Optec focuser adds another couple thou. So, is it worth it?

It doesnt appear that quartz optics and carbon fiber actually eliminate the need for autofocus -- you will have aluminum in your image train anyway (camera, extension tubes etc.) So the goal of thermo-compensation might be better than the goal of zero expansion. 
You still need focusers and focus routines, IMHO. Unless I am missing something.

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Re: Mach2 and Star Trails #Mach2GTO

David Johnson
 

Thanks for the kind words.  Here’s a more conventional video I made last year which shows the no-flip capability of the Mach2 (and other A-P mounts, of course).  It’s very useful for quickly showing people the advantage of counterweight-up operation.


Re: Mach2 and Star Trails #Mach2GTO

Chris White
 

Love it!  I was thinking this was a support thread based on the title. Much cooler than that!