Date   

Re: Elephant Trunk, AP1100AE as a sleep aide

Andrew Burwell
 

This has been a very interesting discussion. I don't know how relevant it is to what is being discussed. But I have looked up and down the market for a premium 8" reflector system that works at longer focal lengths. I'm currently using an 8" edge for 2000mm imaging. The light weight and size makes it ideal as the "largest travel scope" you could potentially use (depending on what you consider travel ready). Premium scopes exist in all sizes up to 6" refractors (some very premium come larger) then you jump to reflectors at 10" and skip 8" sizes for premium made scopes. This is likely due to the economics of making one. But as far as I know there is no premium 8" scope. Today with many portable mounts being introduced that can carry 35 lbs, there might be a market for such a scope. I certainly would prefer one over using an Edge, but currently the Edge is my only choice and if I'm willing to accept lower focal length you can use an 8" RC. But both those scopes are non premium and have poor mechanical issues that considerably increase the cost to address.

-Andrew


Re: Elephant Trunk, AP1100AE as a sleep aide

Emilio J. Robau, P.E.
 

I wanted to comment that I really enjoy these discussions regarding the design aspects of scopes and the things that Roland and others think of when they discuss these issues on line.  I have nothing to contribute but a thanks to several participants and Roland for pointing out the finer details of the various offerings on the market.

Back to lurking.


Re: Elephant Trunk, AP1100AE as a sleep aide

Roland Christen
 

The main issue for me is that it is impossible to compete with a 10" astrograph at $4k where users cannot discern the difference. A scope with 66% obstruction will have meaningful contrast reduction. Once the obstruction exceeds 45 - 50% there is a rapid decline in image contrast, most notably on stars. That's because the central Airy Disc shrinks to below 40% and the diffraction rings have as much or more energy as the central disc. For a 66% obstruction the relative intensity of the central Airy disc is only 30% versus 70% for the surrounding diffraction rings. Any slight atmospheric motion, or long exposure imaging, will diffuse those rings into a fairly large blur which will be larger than what you can image with a very much smaller scope that doesn't have an obstruction.

For more specifics look here:
https://www.telescope-optics.net/obstruction.htm

Rolando


-----Original Message-----
From: Roland Christen via groups.io <chris1011@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Mon, Sep 26, 2022 12:46 pm
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

The Tak is definitely a good instrument. I have seen results from a 300mm version and the images were sharp across the field of a 9 micron chip.

We now have a number of inexpensive 10" wannabe Mewlons coming from Asia. One in particular I noticed has an intensive review on CN. Looks well built with good machining, etc. https://www.cloudynights.com/topic/790201-sharpstar-sca260-unboxing-impressions/
Don't know about the optical performance, but I immediately noticed things that most users have no clue about.

Specs for this scope as listed by the manufacturer:
  • Primary mirror aperture: 260mm
  • Focal length/focal ratio: 1300mm/f5
  • Primary mirror type: Aspherical reflective mirror
  • Primary mirror material: PZ33 (same as pyrex glass)
  • Corrector rear group combination: Three element air-spaced lens structure
  • Minor axis diameter of the secondary mirror: 120mm
  • Secondary mirror holder diameter: 150mm
Notice that the stated central obstruction is 150mm, or 58%. By itself that's not too bad for an imaging scope with a wide field coverage. However, one of the unboxing images that the user took, he showed the view of the from the focuser end of the actual optical aperture (see below). If you scale the image so that the secondary obstruction is 150mm, then the actual mirror clear aperture is 228mm (the image shows 66% obstruction). The mirror may indeed be 260mm, but they added an aperture ring around the mirror's outer diameter, probably to eliminate edge defects. It reminds me of the RC Optical scopes that were imported from LOMO some years ago. The aperture ring was needed to control the turned edge defects caused by rapid polishing of aspherical surfaces.



-----Original Message-----
From: weems@...
To: main@ap-gto.groups.io
Sent: Sat, Sep 24, 2022 11:56 pm
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

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

Bill Long
 

From my discussions with an owner of that SCA260 it was pretty good up to an APSC field. Past that it wasn't very well corrected. They also seem to lose their collimation rather easily, requiring adjustments anytime the scope was moved. Most early adopters sold the scope and moved on from it.





From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Roland Christen via groups.io <chris1011@...>
Sent: Monday, September 26, 2022 10:46 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide
 
The Tak is definitely a good instrument. I have seen results from a 300mm version and the images were sharp across the field of a 9 micron chip.

We now have a number of inexpensive 10" wannabe Mewlons coming from Asia. One in particular I noticed has an intensive review on CN. Looks well built with good machining, etc. https://www.cloudynights.com/topic/790201-sharpstar-sca260-unboxing-impressions/
Don't know about the optical performance, but I immediately noticed things that most users have no clue about.

Specs for this scope as listed by the manufacturer:
  • Primary mirror aperture: 260mm
  • Focal length/focal ratio: 1300mm/f5
  • Primary mirror type: Aspherical reflective mirror
  • Primary mirror material: PZ33 (same as pyrex glass)
  • Corrector rear group combination: Three element air-spaced lens structure
  • Minor axis diameter of the secondary mirror: 120mm
  • Secondary mirror holder diameter: 150mm
Notice that the stated central obstruction is 150mm, or 58%. By itself that's not too bad for an imaging scope with a wide field coverage. However, one of the unboxing images that the user took, he showed the view of the from the focuser end of the actual optical aperture (see below). If you scale the image so that the secondary obstruction is 150mm, then the actual mirror clear aperture is 228mm (the image shows 66% obstruction). The mirror may indeed be 260mm, but they added an aperture ring around the mirror's outer diameter, probably to eliminate edge defects. It reminds me of the RC Optical scopes that were imported from LOMO some years ago. The aperture ring was needed to control the turned edge defects caused by rapid polishing of aspherical surfaces.



-----Original Message-----
From: weems@...
To: main@ap-gto.groups.io
Sent: Sat, Sep 24, 2022 11:56 pm
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

--
Roland Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

Roland Christen
 

The Tak is definitely a good instrument. I have seen results from a 300mm version and the images were sharp across the field of a 9 micron chip.

We now have a number of inexpensive 10" wannabe Mewlons coming from Asia. One in particular I noticed has an intensive review on CN. Looks well built with good machining, etc. https://www.cloudynights.com/topic/790201-sharpstar-sca260-unboxing-impressions/
Don't know about the optical performance, but I immediately noticed things that most users have no clue about.

Specs for this scope as listed by the manufacturer:
  • Primary mirror aperture: 260mm
  • Focal length/focal ratio: 1300mm/f5
  • Primary mirror type: Aspherical reflective mirror
  • Primary mirror material: PZ33 (same as pyrex glass)
  • Corrector rear group combination: Three element air-spaced lens structure
  • Minor axis diameter of the secondary mirror: 120mm
  • Secondary mirror holder diameter: 150mm
Notice that the stated central obstruction is 150mm, or 58%. By itself that's not too bad for an imaging scope with a wide field coverage. However, one of the unboxing images that the user took, he showed the view of the from the focuser end of the actual optical aperture (see below). If you scale the image so that the secondary obstruction is 150mm, then the actual mirror clear aperture is 228mm (the image shows 66% obstruction). The mirror may indeed be 260mm, but they added an aperture ring around the mirror's outer diameter, probably to eliminate edge defects. It reminds me of the RC Optical scopes that were imported from LOMO some years ago. The aperture ring was needed to control the turned edge defects caused by rapid polishing of aspherical surfaces.



-----Original Message-----
From: weems@...
To: main@ap-gto.groups.io
Sent: Sat, Sep 24, 2022 11:56 pm
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

--
Roland Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

Eric Weiner
 

The Mewlon 250s are in a production halt due to the unavailability of parts, the focusing mechanism in particular. This comes from Chris Hysinger at Tak America. I had a 250 on order for 2+ years and ended up changing to a 210 which is now in my possession. Not the most imaging capable OTA but Chris says it could be 3-5 years on the 250 or 300. Of course, you could find a used one.

Eric


Re: Elephant Trunk, AP1100AE as a sleep aide

Roland Christen
 

The main difference is that the Mewlon is open tube and has spider diffraction. Open tube leaves the mirror coatings vulnerable to atmospheric schmutz. Some people love spider diffraction, some don't.

Rolando

-----Original Message-----
From: weems@...
To: main@ap-gto.groups.io
Sent: Sat, Sep 24, 2022 11:56 pm
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

--
Roland Christen
Astro-Physics


Re: Unwanted AP1600 Mount Passenger

Roland Christen
 


The only place where it could have entered the mount was where the through-mount power/usb cables enter the back of the mount.
Actually, the place they can get in is on the top of the Dec axis where the cables come out. There are two holes which are used for thru-mount cables. That is where a mouse entered my 1600 mount. I have since taped them shut.

Roland

-----Original Message-----
From: Patrick Sparkman via groups.io <psparkman@...>
To: main@ap-gto.groups.io
Sent: Sat, Sep 24, 2022 8:19 pm
Subject: [ap-gto] Unwanted AP1600 Mount Passenger

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!


--
Roland Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

Karen Christen
 

Well that’s downright gorgeous, Linwood!

Karen

AP

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of ap@...
Sent: Monday, September 26, 2022 10:14 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Elephant Trunk, AP1100AE as a sleep aide

 

I received some helpful feedback, and also some help with StarXTerminator from the vendor (excellent support).  I did a new version and welcome further feedback.  Below is my original for comparison, and the new version afterwards.  I managed to get considerably smaller stars, and left in some green and added a bit more saturation to some of the colors for (hopefully) a bit more interesting background.

Full size version at Astrobin: 

https://www.astrobin.com/85ed5q/B/

Criticism and comment always welcomed.

Linwood



 


--
Karen Christen
Astro-Physics


Re: Elephant Trunk, AP1100AE as a sleep aide

ap@CaptivePhotons.com
 

I received some helpful feedback, and also some help with StarXTerminator from the vendor (excellent support).  I did a new version and welcome further feedback.  Below is my original for comparison, and the new version afterwards.  I managed to get considerably smaller stars, and left in some green and added a bit more saturation to some of the colors for (hopefully) a bit more interesting background.

Full size version at Astrobin: 

https://www.astrobin.com/85ed5q/B/

Criticism and comment always welcomed.

Linwood



 


AP 600E goto question

thefamily90 Phillips
 

Set up my AP 600E last night and had a problem. First of all I did not have a CP2 control box (I have one but not with me). The other thing is that the one non-Y cable going from the mount to the control box would not plug into the control box until I added an extension which fit.
So, something above may be the root of my problem but here’s what happened. When I connected everything and plugged in the power the red light came on and the keypad lit up. After going through the steps I noted that went on the sidereal drive, the amount was moving toward the east and right ascension. It was moving slowly, but faster than if I turned the power off and watched the object drift toward the west. I know I must be doing something wrong but if anybody has anything to suggest I would appreciate it.

Jim P


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