16 replies to this topic

[TicoWiko]

I'm the happy new owner of an AM5N + C9.25 XLT combo. The main purpose of the rig is to serve as a compact(ish) alternative to my 10" dob for visual astronomy. The C9.25 is of course also a wonderful instrument for planetary AP, which I have just gotten started on last night (first capture ever, yay me !). For DSO AP, while it's not impossible to make it work, as many have pointed out to me it'll certainly be one hell of a challenge for a complete beginner. So I took the advice of my betters and am now in the market for a small APO to fill that final niche.

 

On the other hand, my only disappointment with the rig so far is the goto accuracy. The tracking is great, but the pointing is way off even after multi star alignment. My first night with it was horrendous on that point, though on my second night I've managed to improve it quite a bit with a few simple tricks (more stable ground, syncing to stars around my final target, etc.), though it's still far from perfect and works best close to synced objects. While perfect gotos might be a bit of a luxury, I feel like they could really make an observing session so much more carefree. One drastic solution that's been suggested to me is stick a guidescope on top and have it platesolve for me, and there of course I can expect absolute perfection (up to questions of flexure, but though that may be an important issue for AP, I'm assuming it can't get so bad as to drastically impact casual visual observation). At first, I really wanted to avoid this route because I could already imagine the tangle of extra cables and hardware and installation woes that this would entail. While that's the norm for AP, it would kinda suck the fun out of a visual session where I just want to point at things and look at them.

 

So why am I bringing up both those problems at the same time in the refractor forum ? Because I realized that combining the ASI2600MC Air with a small APO, I might actually be able to hit 2 birds with one stone. I could mount the small APO on top of the C9.25 as a guidescope with the 2600Air, and the cabling would be kept to a bare minimum : external DC power to the 2600Air, DC output from the 2600Air to the AM5N (ZWO recommends that order rather than the opposite), then a usb C connection from the 2600Air to the AM5N. That's it : 3 cables, 2 of which rotate end to end with the scope so no snagging, and power supply snagging or curling is a potential issue not matter what. And I'd have a perfect plate solving goto system attached to a wonderful visual instrument that I could completely control from my phone. And then of course, I could just use the APO alone with the 2600Air to start my DSO AP journey, with the added benefit that the 2600Air being an all in one package would make an easier introduction to DSO AP.

 

So is this an utterly nonsensical idea or a very efficient solution to both my needs ? If the former, what's wrong with my reasoning ? If the latter, I'm very open to scope recommendations !

 

The APO in question needs to illuminate a fairly large field, not merely to fully illuminate the APS-C sensor of the 2600Air, but to make sure the integrated guide cam is well illuminated. I believe the recommendation is to have a scope that can illuminate a full frame. For guiding, I'm not sure how much it matters if the outer edges of the frame are aberrated as long as they're well illuminated. On the other hand, I'd like to keep it fairly small and lightweight to let me still utilize my rig without counterweights when it serves as a guide scope on top of the C9.25. Is there a 2600Air compatible APO that weighs under 2 kgs ? The lighter the better. Given that I'm looking for something small I don't expect the price to go too far above 1k, but if something perfectly suits my needs and it's more expensive then so be it.

 

And of course, if anyone is familiar with the 2600Air and in particular the user experience end of things, I'd love to hear if you think this can indeed lead to hassle free observation sessions, after a bit of setup perhaps. Simply put, how user friendly is the interface if I want to use plate solving to perfectly guide to a target ? I'd also like to avoid throwing in an autofocuser. Is it easy enough to manually focus my guidescope using the image preview ? Feel free to add anything about the 2600Air I may be missing.

 

Clear skies

Edited by TicoWiko, 20 March 2025 - 08:02 AM.

[scanner97]

Quick comments...

 

In general, many APOs are fine with APS-C but not quite so much with a FF.  And there is a question of both the full field illumination (not sure about the 9.25 with FF) and whether the field is flat all the way.  Also matters how much you like to look at pixels; every person's tolerance is different.

 

The 2600 is APS-C, not FF.

 

The Askar FMA 180 comes to mind as a small frac that can double nicely.

 

Most folks using SCTs would tell you that you're much better off using an OAG rather than a separate guide set-up.

 

So, it's complicated and there are trade-offs...

 

Good luck!

[TicoWiko]

Quick comments...

 

In general, many APOs are fine with APS-C but not quite so much with a FF.  And there is a question of both the full field illumination (not sure about the 9.25 with FF) and whether the field is flat all the way.  Also matters how much you like to look at pixels; every person's tolerance is different.

 

The 2600 is APS-C, not FF.

 

The Askar FMA 180 comes to mind as a small frac that can double nicely.

 

Most folks using SCTs would tell you that you're much better off using an OAG rather than a separate guide set-up.

 

So, it's complicated and there are trade-offs...

 

Good luck!

Thanks for the feedback, but I think you're not quite getting what I'm going for here. To be fair it's a bit of an uncommon combo and maybe I wasn't clear.

 

I agree that if I wanted to do DSO AP with the C9.25, I'd go for an OAG. But I'm *not* going to do that, that sounds really hard when just starting out haha. The reason for wanting a guide scope with a 2600Air *on the guide scope* is to have live plate solving during visual sessions for perfect gotos. You can't plate solve off an OAG from what I gather, especially with an FL as long as a C9.25, the field is rather tiny. So the point of the guide scope isn't really guiding : it's just plate solving then pointing. It can then also help to guide if needed, but the native guiding of the AM5N is overwhelmingly good enough for visual use.

 

The second usage I would get out of the APO is as a DSO astrograph using the 2600Air. Yes I realize it's an APS-C sensor, but the guiding sensor is a bit further away still from the main sensor, so I'm not sure how large the illuminated field really needs to be, though likely a bit beyond APS-C. Feedback from people who've used either the 2600Air or 2600Duo would really help here...

 

Hope that's clearer !

[scanner97]

Ok, got it.  You could definitely do that.  I imagine you would just need to treat the APO as your main scope in the Air.  (I don't own one so can't comment on either the Air in general or the 2600 version.  But the 571 sensor is great.)  The AM5 tracking is plenty good enough for visual use if you just want a solved goto from the APO.  (You'll need to make sure it's well aligned with the 9.25 though!)  And the FMA would make a fine introduction to AP.  It's short enough that you could do decent unguided exposures and get plenty of experience processing a range of images.

[afd33]

As long as the mount can handle the extra weight it can work. I know a guy that used to use a William Optics Z61 as a guide scope. His reasoning was that it was basically their Guidestar 61 guide scope except better.

[TicoWiko]

Ok, got it. You could definitely do that. I imagine you would just need to treat the APO as your main scope in the Air. (I don't own one so can't comment on either the Air in general or the 2600 version. But the 571 sensor is great.) The AM5 tracking is plenty good enough for visual use if you just want a solved goto from the APO. (You'll need to make sure it's well aligned with the 9.25 though!) And the FMA would make a fine introduction to AP. It's short enough that you could do decent unguided exposures and get plenty of experience processing a range of images.

Yeah it looks about as tiny as can be, which fits the bill. But no need for unguided exposures, the 2600Air should provide guiding pretty seamlessly. That's the whole point of it : it includes a guiding sensor on the same plane as the main sensor, and has an integrated mini pc in the body.

[scanner97]

Sounds like the 2600Air includes both the Air and the guide chip.  You could certainly get some experience with guiding an APO that way, and eventually try to guide the 9.25 with it.  It's basically like having an OAG without the whole OAG unit. 

 

And you can always look at larger APOs than the FMA depending on what you want to shoot with it.  You will need to keep the total payoad in mind though.  With another scope riding on top of the 9.25, you'd probably want to use counterweights before you get to 30 lbs. total weight.  

[TicoWiko]

Sounds like the 2600Air includes both the Air and the guide chip. You could certainly get some experience with guiding an APO that way, and eventually try to guide the 9.25 with it. It's basically like having an OAG without the whole OAG unit.

And you can always look at larger APOs than the FMA depending on what you want to shoot with it. You will need to keep the total payoad in mind though. With another scope riding on top of the 9.25, you'd probably want to use counterweights before you get to 30 lbs. total weight.

Yeah I agree a slightly larger APO might be better for just AP, but the FMA is so light it would really help keep the setup simple. It's cheap enough that I can start with it for both purposes and keep it as just a guide scope when I eventually upgrade.

[Cliff Hipsher]

What I would have done was buy the "regular" ASI2600 Pro Duo and get a 256gig Air Plus.  This new 256g version has BlueTooth which will let you connect Air Plus to a BT enabled mount with NO USB cable involved.  I run my AT80ED/AM3 rig that way.

 

Another selling point is there is very little cost differential between the 2600MC ProDuo Air and buying a separate 2600MC ProDuo and a 256gig Air Plus.

 

One thing that will clean up the GoTo issue is turning on GoTo Auto-Center.  In fact, once I get my 3 mounts polar aligned I don't sync to any stars, I just have at it and run the imaging plans that I have set up for each rig and let Air do its thing.

 

As a side note, I used to have to play the Star Alignment game with my LXD75.  I fixed that by ditching the AutoStar stuff (which required the performing a star alignment before tracking was turned on..) and installing an OnStep Go-To drive system which is compatible with Air, ASCOM, and INDI based controllers.

 

For the APO stuff, check with our sponsor AstroNomics .

[TicoWiko]

What I would have done was buy the "regular" ASI2600 Pro Duo and get a 256gig Air Plus. This new 256g version has BlueTooth which will let you connect Air Plus to a BT enabled mount with NO USB cable involved. I run my AT80ED/AM3 rig that way.

Another selling point is there is very little cost differential between the 2600MC ProDuo Air and buying a separate 2600MC ProDuo and a 256gig Air Plus.

One thing that will clean up the GoTo issue is turning on GoTo Auto-Center. In fact, once I get my 3 mounts polar aligned I don't sync to any stars, I just have at it and run the imaging plans that I have set up for each rig and let Air do its thing.

As a side note, I used to have to play the Star Alignment game with my LXD75. I fixed that by ditching the AutoStar stuff (which required the performing a star alignment before tracking was turned on..) and installing an OnStep Go-To drive system which is compatible with Air, ASCOM, and INDI based controllers.

For the APO stuff, check with our sponsor AstroNomics .

So one thing to keep in mind is the issue I'm trying to solve is purely for visual sessions, so no imaging plans involved. And the aim is to keep things as compact as possible with as few extra accessories as possible. I don't really follow the advantage of a separate AsiAir, even if it's BT enabled. It may be one less USB cable, but it'd also be an extra power cable, and an extra piece of equipment to bring along and set up. The 2600Air can be connected to wirelessly : I would have a tablet just connect to the 2600Air wifi and control everything through there. Or am I missing another advantage to the AsiAir perhaps ?

And thanks for the link, but I'm in Europe

[Sk240]

I have used my AM5 for visual use with my 120mm refractor and I agree that the goto accuracy for visual use is not very good. The trick you mentioned about syncing to a nearby star before going to the actual target does help.

I tried mounting a guidescope and then using using the Asiair to platesolve. That works well but you have to align the guidescope to the main scope and that takes work too, along with the normal polar alignment stuff.


Honestly it just felt like trying to play basketball wearing running shoes. It will work but it isn't what the running shoes is primarily designed to do. If it was really designed for visual use then they should've paired it with a better hand controller.

I feel that an alt az goto mount is more designed for visual use and maybe a better option, as is attaching a Celestron starsense phone mount to the C9.25 and using it with manual mount.

[Cliff Hipsher]

Some of you guys don't get it.  Air uses the MAIN optics and camera for Polar Alignment and  GoTo Auto-Center FOR ASTORPHOTOGRAPHY WORK,  so using a guide scope arrangement to do those things is counter productive.  The only thing you can do with a guide scope is guide the mount.  HINT:  Air is an Astrophotography tool so how can you expect a 2600 Air to help you find things for you to eyeball?

 

The sad thing is I'm feeling like a putz because I didn't catch the visual part, but the again I'm laughing in my sleeve at the same time.

 

See Y'All in the funny papers.

[TicoWiko]

Some of you guys don't get it. Air uses the MAIN optics and camera for Polar Alignment and GoTo Auto-Center FOR ASTORPHOTOGRAPHY WORK, so using a guide scope arrangement to do those things is counter productive. The only thing you can do with a guide scope is guide the mount. HINT: Air is an Astrophotography tool so how can you expect a 2600 Air to help you find things for you to eyeball?

The sad thing is I'm feeling like a putz because I didn't catch the visual part, but the again I'm laughing in my sleeve at the same time.

See Y'All in the funny papers.

Counter productive to what exactly ? I expect it to find things for me to eyeball the same way I expect it to find things for me to image...

Using a guidescope for perfect visual gotos is common enough that I've had multiple people recommend that path to me. What exactly does it mean to say "FOR ASTORPHOTOGRAPHY WORK" ? If it works, it works, regardless of if the final destination is my eyeball or a sensor.

[Cliff Hipsher]

Whatever cranks your tractor...

[Celerondon]

Counter productive to what exactly ? I expect it to find things for me to eyeball the same way I expect it to find things for me to image...

Using a guidescope for perfect visual gotos is common enough that I've had multiple people recommend that path to me. What exactly does it mean to say "FOR ASTORPHOTOGRAPHY WORK" ? If it works, it works, regardless of if the final destination is my eyeball or a sensor.

 

 

We know that your idea will work, because it already has.  Some of us are already “cheating” by using a secondary optical system for plate solving.  The idea of installing and using such a system on a visual rig sometimes evokes a visceral negative reaction from people even though your way would keep wires to a minimum while easing polar alignment and enhancing GoTo accuracy.  
 

If you mount that apo in an adjustable ring mount then aligning its aim to match that of your primary telescope should be as easy as aligning a finder.  Although YouTube reviewers have reported that the guide sensor in the Duo cameras is tolerant of misshaped off-axis stars, this capability won’t matter for this particular application because you will be using the main sensor. 
 

This is an interesting concept.  Please let us know how your rig turns out.  
 

Don

 

Rings like these

[BucketDave]

I have an FMA180 and most of the time, it sits in finderscope rings, solidly attached to my GEM45. Paired with an ASI174mm, it makes a great finderscope for my 8 inch ACF.

Although i aim to use an OAG to guide the ACF
I sometimes struggle to find enough guide stars (light pollution + imaging at F10). That's when the FMA180 kicks back into action, as a guidescope. I generally find the two methods to priduce comparable guiding.

[TicoWiko]

We know that your idea will work, because it already has.  Some of us are already “cheating” by using a secondary optical system for plate solving.  The idea of installing and using such a system on a visual rig sometimes evokes a visceral negative reaction from people even though your way would keep wires to a minimum while easing polar alignment and enhancing GoTo accuracy.  
 

If you mount that apo in an adjustable ring mount then aligning its aim to match that of your primary telescope should be as easy as aligning a finder.  Although YouTube reviewers have reported that the guide sensor in the Duo cameras is tolerant of misshaped off-axis stars, this capability won’t matter for this particular application because you will be using the main sensor. 
 

This is an interesting concept.  Please let us know how your rig turns out.  
 

Don

 

Rings like these

Thanks for the practical feedback ! If I get this to work I will for sure be back to brag about it haha. I actually already got the FMA180 Pro, and will play around with it as a wide field imager with my ASI 585 MC Pro as soon as the clouds go away. I just went ahead and got it because frankly it seems dirt cheap compared to the very impressive results I've seen online from it. The 2600Air is a more sizeable investment, meaning I'm going to nitpick it to death before pulling the trigger, so it will be a little while longer before I pull the trigger. One thing I'm wondering, for reasons you'll see below, is if I can use the 2600Air as a main camera, but still configure a separate guidescope as my guider, or if the Air software will insist that I use the secondary sensor on the 2600 as my guider. The reason is that while the native setup of the 2600Air will often work for me, there is at least one scenario where I'd rather use a guidescope, but still be fine with the 2600 main camera, and the onboard Air of course.

 

And a couple of people have mentioned this would all make PA easier, but in the case of visual, I wouldn't even bother with that. I would just set up the AM5N in AZ mode, so setup would be even simpler.

 

Edit : Just had a look at Cuiv's video, and he mentions the possibility, and it seems the only constraint is that it has to be a ZWO camera as well. Very seriously considering buying this now. My poor wallet XD

 

I have an FMA180 and most of the time, it sits in finderscope rings, solidly attached to my GEM45. Paired with an ASI174mm, it makes a great finderscope for my 8 inch ACF.

Although i aim to use an OAG to guide the ACF
I sometimes struggle to find enough guide stars (light pollution + imaging at F10). That's when the FMA180 kicks back into action, as a guidescope. I generally find the two methods to priduce comparable guiding.

Yep, I'm thinking of something similar when I eventually try to use my C9.25 for DSO (not happening tomorrow, I'm still too much of a noob for that long of a focal length I think). Illuminating an APS-C with a reduced C9.25 is doable without too much vignetting, but I think it might be too demanding for an OAG and likely wouldn't illuminate the secondary sensor of the 2600Air enough. One annoying limitation of most software out there though is they won't let you plate solve using your guidescope. This is a shame because it's rather common for your guidescope to have a wider FOV than your main camera, making platesolving easier. I'm pretty sure neither Nina nor the Air will let you do it. You could technically "lie" and switch your main camera, platesolve to target, then switch it all back, but it seems weird to need that workaround for what I think is a fairly common need.

Edited by TicoWiko, 22 March 2025 - 08:59 PM.