Let's Talk Semi-High End Telescopes for my AP1600GTO Mount - Forums

My dream has partially come true, and I am now the proud owner of an Astro-Physics AP1600GTO (albeit a 2013 model). And I finished my ROR observatory a couple of months ago.

Logically, I needed an observatory before I could buy a large, high-end mount like the 1600GTO. And of course, I needed the high-end mount before I could purchase a high-end telescope.

Now that I have both, I am ready for a high-end telescope. Except now I’m almost broke!! My budget has been all but tapped!

Hence the title of this thread “let’s talk SEMI-High-End mounts.”

Since I really love imaging galaxies and small, odd (less commonly imaged) nebula, I was thinking I want to be at a long focal length. I love the images I see caught with the CDK24 and CDK17 (focal lengths of 3974mm and 2939mm, respectively). I know the 1600GTO can handle long FL without issue.

Since I am nowhere near being able to afford CDKs, I was thinking a Celestron C14-XLT (Non EdgeHD) with a Starizona large format reducer might be a good compromise. I can buy one used for somewhere in the 2K plus range.

That said, I am interested in what others might do if they had a $3000.00 budget. What other “semi-high end” scopes might I buy worthy of my 1600GTO that I can find used for 3K?

My appreciation to anyone who cares to respond.

Congrats on the new gear and obsy!! really makes astrophotography even more enjoyable!! With the non-edge hd versions you're going to deal with some mirror flop and focusing instability especially with the larger versions.

There is also the option if willing to deal with the headache of collimation at first and finding a used 12” or 14” gso truss RC that also has a great reducer from ts-optics. I had the 12” with the large format reducer and it produced amazing images once I got collimation figured out.

I am honestly unsure what I would do given your budget as I am known for making rush decisions and regretting it haha

If I was in your position, I would go with a more solid design in a smaller aperture, try and make your new set up as headache free as possible while still retaining a balance of aperture and focal length for the fun smaller stuff!!

sorry, probably didn’t help much haha

I presently have a C11, so far no issues with it. When the mirror flops, it only effects one image because “Autofocus” and “Recenter After Drift” kicks in and corrects for it (using NINA). I also have the option of adding an external focuser, although I have to see if I have the Backfocus room available. I should, but I might have to lose the auto camera angle-adjuster (CAA).

I always wanted an RC but I hear such nightmare stories about collimation. I’m afraid to give it a try. I know a couple of people who gave up and returned their RCs before the 30-day window for returns expired.

I see you already have a C925. While the aperture is larger, you’ll be extremely oversampled with the C14. Of course you can resample for better SNR but that still means the FOV is tiny unless you also go with a larger camera and, accordingly, filters from the IMX585 camera you have - a considerable investment. So unless you setup remote, I’ld actually recommend a 10” imaging Newtonian at f/4 if you can fit it into your observatory. It’ll give you great pixel and total etendue and you’ll be sampled well. And for your budget you’ll be able to buy something nice with few compromises.

I have a truss RC from CFF. Over your budget, probably, but leagues ahead of the GSO offerings.

I have a IMX571 CMOS that I can bin 2X or 3X in Pixinsight. It immediately demolishes any noise and sharpens the stars. Do you think it’s better to be well-sampled natively?

Also, I’m going for long focal length (small targets), so doesn’t the small sensor help?

If you are going to go with a reducer on the C14, why not just save some money and get a C11 and no reducer? If you can somehow swing the Edge version I would highly recommend that route.

There’s an 11” Edge with Pelican case on Amart right now for under your price.

Jeffery Richards · Sep 27, 2025 at 11:15 AM
If you are going to go with a reducer on the C14, why not just save some money and get a C11 and no reducer? If you can somehow swing the Edge version I would highly recommend that route.

My long term plan is to get into planetary eventually, so I’d like the flexibility. Also, I’ve read on the forums that a C11 or C14 with a Starizona Reducer/Corrector makes for better optics than the C11 or C14 natively. I didn’t believe it until I tried it myself last year with my C11 and I definitely saw a significant improvement in my test images.

The C14 with the reducer is significantly cheaper than the EdgeHD-14. Although maybe not the EdgeHD-11.

Not an expert but I love the Takahashi TOA 130 which I use and the Stellarvue Raptor 140 - I’ve seen data from the SVT 180 as well and it’s amazing. Takahashi also has the super fast epsilons which I’ve heard are awesome but maybe a bit more tricky to use. but now I’ve ruined your budget -I use with a C3 Moravian and the field is big but you can crop in…. probably not helpful lol

Michele Bayliss · Sep 27, 2025, 02:56 PM
Not an expert but I love the Takahashi TOA 130

The entire Takahashi telescopes are just beautifully made (inside and out). I might get one in the future but for now I’m looking for the long reach. Thanks for the reply.

Tommy Mastro · Sep 27, 2025 at 04:22 AM
I presently have a C11, so far no issues with it. When the mirror flops, it only effects one image because “Autofocus” and “Recenter After Drift” kicks in and corrects for it (using NINA). I also have the option of adding an external focuser, although I have to see if I have the Backfocus room available. I should, but I might have to lose the auto camera angle-adjuster (CAA).
I always wanted an RC but I hear such nightmare stories about collimation. I’m afraid to give it a try. I know a couple of people who gave up and returned their RCs before the 30-day window for returns expired.

I grow tired of people talk about collimation as if it’s something hard or to be feared. You learn to do it and it takes a few minutes should you ever have to do it. Very simple task. There’s harder things in life. Going to work every day for 45 years. Raising children. Waking up in the morning. Collimation isn’t one of them.

For you perhaps, but you seem to be in the minority.

Matthew Proulx:
Tommy Mastro · Sep 27, 2025 at 04:22 AM

I presently have a C11, so far no issues with it. When the mirror flops, it only effects one image because “Autofocus” and “Recenter After Drift” kicks in and corrects for it (using NINA). I also have the option of adding an external focuser, although I have to see if I have the Backfocus room available. I should, but I might have to lose the auto camera angle-adjuster (CAA).

I always wanted an RC but I hear such nightmare stories about collimation. I’m afraid to give it a try. I know a couple of people who gave up and returned their RCs before the 30-day window for returns expired.

I grow tired of people talk about collimation as if it’s something hard or to be feared. You learn to do it and it takes a few minutes should you ever have to do it. Very simple task. There’s harder things in life. Going to work every day for 45 years. Raising children. Waking up in the morning. Collimation isn’t one of them.

I mean, that hardly seems like a ringing endorsement for the simplicity of collimation 😀. A lot of things are simpler than raising kids or going to work everyday for 45 years. That does not mean they are simple in an absolute sense.

I wouldn‘t call RC collimation easy. It‘s an order of magnitude more difficult than collimating my Epsilon. And I could never successfully collimate the 8“ GSO RC after it lost factory collimation.

Torben van Hees · Sep 27, 2025, 04:14 PM
I wouldn‘t call RC collimation easy. It‘s an order of magnitude more difficult than collimating my Epsilon. And I could never successfully collimate the 8“ GSO RC after it lost factory collimation.

You just haven’t learned the proper method. It is impossible to not have been able to collimate your RC if all the mechanical parts were where they should have been and the distance between the 2 mirrors were where they should have been. You did something you did not understand and could not recover. Simple as that.

Does your seeing support such an oversampled image scale? If you have a C11 with Starizona reducer, I don’t think you’ll see a significant benefit to a C14 for DSO astrophotography. My seeing in Colorado is generally average and I’ve used a 10” f4 newt, and even an incredible AG optical IDK 10”, but my average FWHMs (in arcseconds) actually improved when I went to a TOA-130.

For planetary and visual, I understand that aperture wins since your eyes or lucky imaging will pick out the best moments of seeing. But for longer exposures of small objects, particularly with the camera you have with small pixels, I’d tend to go for the 4-5” APO refractor to complement your larger SCTs. 1000mm FL is pretty well sampled with your camera already at good seeing. Obviously, larger apertures allow resolving slightly dimmer point sources and collecting more photons for a small target that still fits in your FOV (although spread over more pixels since the FOV is likely narrower). But will likely not give you more detail of structures unless you have exceptional seeing.

I personally wouldn’t invest in apertures over 10”-12” for DSO imaging unless my scope will be in a place with good-exceptional seeing on a semi-regular basis. I’d invest in a mono camera/filter with a wider FOV than the 585 before I’d invest in a larger scope. That would benefit your SQA55 as well. You already have the 2” filters, so it would be well under your budget. You can pick up an ASI2600mm for about $1k used or even an ASI6200 for about $3k. And keep the 585 for planetary imaging.

And then later, I’d do a 10-12” IDK or RC to cover that frame in the future.

something went wrong with this post. Deleted.

Rick - I have the ToupTek IMX571-mono, which is the equivalent of the asi2600, which is what I would be using with the 14”, not the 585 sensor. Although I have used the C11 with my 585 and just binned 2X in Pixinsight and it came out great.

I already have an 8” Newt that I love and that works well with either camera without binning. Buying a 10” Newt would be 1000mm to my 800mm. Not much gained there except the slightly larger aperture.

Also - remember that the reason for the 14” is not more aperture, but long FL (reach).

Matthew Proulx · Sep 27, 2025 at 04:18 PM
Torben van Hees · Sep 27, 2025, 04:14 PM
I wouldn‘t call RC collimation easy. It‘s an order of magnitude more difficult than collimating my Epsilon. And I could never successfully collimate the 8“ GSO RC after it lost factory collimation.
You just haven’t learned the proper method. It is impossible to not have been able to collimate your RC if all the mechanical parts were where they should have been and the distance between the 2 mirrors were where they should have been. You did something you did not understand and could not recover. Simple as that.

Actually, I can collimate the 10“ CFF RC I own. I would not call it easy, as SCT collimation, but it‘s a skill one can learn.

I got close with the same methods with the 8“ GSO RC. But only close. Even factory collimation was not correct - but it was ok-ish for M4/3. The design of the primary mirror collimation mechanism is flawed (much too coarse, and sticture - CFF is smooth, and has much finer screws) and the whole tube is not rigid enough to keep the collimation when you slew around the sky. These are both well-known problems with these tubes. Everyone who says it‘s easily achievable I‘ve asked to produce a well-collimated frame with an IMX571 or larger (no BlurX, of course). I‘ve seen none so far.

Torben van Hees · Sep 27, 2025, 08:45 PM
These are both well-known problems with these tubes.

Just curious: If I was to try an RC, could you recommend one that doesn’t suffer from these issues?

Torben van Hees · Sep 27, 2025, 08:45 PM
Matthew Proulx · Sep 27, 2025 at 04:18 PM
Torben van Hees · Sep 27, 2025, 04:14 PM
I wouldn‘t call RC collimation easy. It‘s an order of magnitude more difficult than collimating my Epsilon. And I could never successfully collimate the 8“ GSO RC after it lost factory collimation.
You just haven’t learned the proper method. It is impossible to not have been able to collimate your RC if all the mechanical parts were where they should have been and the distance between the 2 mirrors were where they should have been. You did something you did not understand and could not recover. Simple as that.
Actually, I can collimate the 10“ CFF RC I own. I would not call it easy, as SCT collimation, but it‘s a skill one can learn.
I got close with the same methods with the 8“ GSO RC. But only close. Even factory collimation was not correct - but it was ok-ish for M4/3. The design of the primary mirror collimation mechanism is flawed (much too coarse, and sticture - CFF is smooth, and has much finer screws) and the whole tube is not rigid enough to keep the collimation when you slew around the sky. These are both well-known problems with these tubes. Everyone who says it‘s easily achievable I‘ve asked to produce a well-collimated frame with an IMX571 or larger (no BlurX, of course). I‘ve seen none so far.

I have not had this problem with the 4 RC8 2 RC10 and 1 RC12 I’ve owned. Amateurs have problems yes if they don’t understand how much tension to apply to individual screws. They only need a couple pounds of torque evenly applied slowly just like a tire on a car and will not lose their tension if you properly do it. Don’t confuse aberration such as astigmatism or tilt from camera with collimation. The RC scopes don’t come with field flatteners so there will be a slight astigmatism at the corners. Balancing this is quite easy slightly out of focus on stars. You can argue but I have results and I have the technical background to prove otherwise.

Tommy Mastro · Sep 27, 2025, 05:31 P
Also - remember that the reason for the 14” is not more aperture, but long FL (reach).

I guess that’s my point. More focal length will just get you MORE oversampled, which will not likely yield and more detail for DSO imaging, just larger, fuzzier images. Aperture is what will give you advantages like resolving dimmer point samples and giving more photons on a given small target (spread over a larger area) and better planetary imaging/viewing at times.

Matthew Proulx · Sep 27, 2025 at 08:57 PM
Torben van Hees · Sep 27, 2025, 08:45 PM
Matthew Proulx · Sep 27, 2025 at 04:18 PM
Torben van Hees · Sep 27, 2025, 04:14 PM
I wouldn‘t call RC collimation easy. It‘s an order of magnitude more difficult than collimating my Epsilon. And I could never successfully collimate the 8“ GSO RC after it lost factory collimation.
You just haven’t learned the proper method. It is impossible to not have been able to collimate your RC if all the mechanical parts were where they should have been and the distance between the 2 mirrors were where they should have been. You did something you did not understand and could not recover. Simple as that.
Actually, I can collimate the 10“ CFF RC I own. I would not call it easy, as SCT collimation, but it‘s a skill one can learn.
I got close with the same methods with the 8“ GSO RC. But only close. Even factory collimation was not correct - but it was ok-ish for M4/3. The design of the primary mirror collimation mechanism is flawed (much too coarse, and sticture - CFF is smooth, and has much finer screws) and the whole tube is not rigid enough to keep the collimation when you slew around the sky. These are both well-known problems with these tubes. Everyone who says it‘s easily achievable I‘ve asked to produce a well-collimated frame with an IMX571 or larger (no BlurX, of course). I‘ve seen none so far.
I have not had this problem with the 4 RC8 2 RC10 and 1 RC12 I’ve owned. Amateurs have problems yes if they don’t understand how much tension to apply to individual screws. They only need a couple pounds of torque evenly applied slowly just like a tire on a car and will not lose their tension if you properly do it. Don’t confuse aberration such as astigmatism or tilt from camera with collimation. The RC scopes don’t come with field flatteners so there will be a slight astigmatism at the corners. Balancing this is quite easy slightly out of focus on stars. You can argue but I have results and I have the technical background to prove otherwise.

Feel free to show a frame. Would be the first I see.

Torben van Hees · Sep 27, 2025, 09:26 PM
Matthew Proulx · Sep 27, 2025 at 08:57 PM
Torben van Hees · Sep 27, 2025, 08:45 PM
Matthew Proulx · Sep 27, 2025 at 04:18 PM
Torben van Hees · Sep 27, 2025, 04:14 PM
I wouldn‘t call RC collimation easy. It‘s an order of magnitude more difficult than collimating my Epsilon. And I could never successfully collimate the 8“ GSO RC after it lost factory collimation.
You just haven’t learned the proper method. It is impossible to not have been able to collimate your RC if all the mechanical parts were where they should have been and the distance between the 2 mirrors were where they should have been. You did something you did not understand and could not recover. Simple as that.
Actually, I can collimate the 10“ CFF RC I own. I would not call it easy, as SCT collimation, but it‘s a skill one can learn.
I got close with the same methods with the 8“ GSO RC. But only close. Even factory collimation was not correct - but it was ok-ish for M4/3. The design of the primary mirror collimation mechanism is flawed (much too coarse, and sticture - CFF is smooth, and has much finer screws) and the whole tube is not rigid enough to keep the collimation when you slew around the sky. These are both well-known problems with these tubes. Everyone who says it‘s easily achievable I‘ve asked to produce a well-collimated frame with an IMX571 or larger (no BlurX, of course). I‘ve seen none so far.
I have not had this problem with the 4 RC8 2 RC10 and 1 RC12 I’ve owned. Amateurs have problems yes if they don’t understand how much tension to apply to individual screws. They only need a couple pounds of torque evenly applied slowly just like a tire on a car and will not lose their tension if you properly do it. Don’t confuse aberration such as astigmatism or tilt from camera with collimation. The RC scopes don’t come with field flatteners so there will be a slight astigmatism at the corners. Balancing this is quite easy slightly out of focus on stars. You can argue but I have results and I have the technical background to prove otherwise.
Feel free to show a frame. Would be the first I see.

📷 Screenshot 2025-09-27 150357.png📷 Screenshot 2025-09-27 150437.png

Tommy Mastro · Sep 27, 2025 at 08:57 PM
Torben van Hees · Sep 27, 2025, 08:45 PM
These are both well-known problems with these tubes.
Just curious: If I was to try an RC, could you recommend one that doesn’t suffer from these issues?

People seem to have better results with the GSO truss tubes - but I still think they‘re not rigid enough in their construction, although very heavy for a carbon construction. The ones from CFF are different, and better. I like mine a lot. And there’s ASA, of course. DSI made some which seem to be of very high quality, too, such a thing might be available used.