I'm about to try unguided imaging on my C14EdgeHD. I have an ASA DDM85 mount which is pretty good with a decent sky model when using a Hyperstar at 712 mm focal length. However I'm unsure how well it would perform at 3910 focal length.
Has anyone succeeded with unguided imaging at 3910 focal length?
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I've seen my fellow astrophotographer in the club doing 5 - 20 mintues unguided exposure with CDK12.5 (2500mm) and 10Micron GM2000HPS .
https://www.astrobin.com/9opyjc/
https://www.astrobin.com/jkqe5u/C/
Absolute encoder and precisely built sky model allowed him taking 20 min unguide exposure.
I doubt if it is possible without AE.
https://www.astrobin.com/9opyjc/
https://www.astrobin.com/jkqe5u/C/
Absolute encoder and precisely built sky model allowed him taking 20 min unguide exposure.
I doubt if it is possible without AE.
This would be possible with the mirror locked and the OTA held in very firm rings such as those provided by software Bisque. The key would be rigidity of the OTA and very accurate polar alignment, balance and excellent sky conditions.
The stock Celestron orange rails are not very rigid and indeed rails may be a source of differential flexure.
The C14's biggest enemy is mirror flop and indeed the stock mirror locks may not hold the mirror firm enough so you may need to consider alternatives.
Protrack offered by Software Bisque through the SkyX & others can help improve the guiding accuracy.
The stock Celestron orange rails are not very rigid and indeed rails may be a source of differential flexure.
The C14's biggest enemy is mirror flop and indeed the stock mirror locks may not hold the mirror firm enough so you may need to consider alternatives.
Protrack offered by Software Bisque through the SkyX & others can help improve the guiding accuracy.
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I use a C14 Edge HD on a Paramount MX+. It does not have absolute encoders but it is a very good mount. I review my polar alignement and my TPoint model (150 stars) with The SkyX on a regular basis. I do not have a PEC (Periodic Error Correction) model because my horizon is obstructed where I should perform the PEC recording.
I shoot with a 0.7x focal reducer at 2700mm and I normally autoguide at full focal length using a ONAG from Innovations Foresight. With that setup, I can shoot 20 minute exposures successfully and lose very few subs over a night. If I do not autoguide, I can shoot 5 or 6-minute subs without losing too many. I can sometimes shoot 10-minute subs but I will lose quite a few due to elongated stars.
Shooting unguided at the native 3910 focal length is a perilous exercise. And if you start drifting and do not have a recentering routine in your telescope operating software (are you using NINA?) you will likely end up with a lot of frames with your target uncentered.
I find that working at f/7,7, it is already pretty slow compared to faster f/4 or f/5 systems. I would not like to shoot with a 2 times slower system at f/11.
May I ask why you do not want to invest in a focal reducer and why you do not want to autoguide, which would make your life easier?
You can check my work and my equipment at https://rogermenard.ca/language/en/ if you so desire.
I shoot with a 0.7x focal reducer at 2700mm and I normally autoguide at full focal length using a ONAG from Innovations Foresight. With that setup, I can shoot 20 minute exposures successfully and lose very few subs over a night. If I do not autoguide, I can shoot 5 or 6-minute subs without losing too many. I can sometimes shoot 10-minute subs but I will lose quite a few due to elongated stars.
Shooting unguided at the native 3910 focal length is a perilous exercise. And if you start drifting and do not have a recentering routine in your telescope operating software (are you using NINA?) you will likely end up with a lot of frames with your target uncentered.
I find that working at f/7,7, it is already pretty slow compared to faster f/4 or f/5 systems. I would not like to shoot with a 2 times slower system at f/11.
May I ask why you do not want to invest in a focal reducer and why you do not want to autoguide, which would make your life easier?
You can check my work and my equipment at https://rogermenard.ca/language/en/ if you so desire.
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I am using an AG Optical 14.5" at 2464mm focal length and can do up to 10 minute unguided exposures with my GM 3000 mount. Although, I typically expose for 3 minutes LRGB filters and 5 Minutes with SHO filters. I also use a 99 point model for the mount.
The Celestron Edge14 has a good optical system but a very mediocre mechanical design. The primary can move and the entire OTA is not super rigid. You might get some useable results by imaging without guiding but why? Guiding is easy and it guarantees that you won't have guide errors due to mechanical flexure or thermal issues. Guiding will also greatly improve your image yield. High quality sky time is valuable so don't throw some of it away by not guiding!
I can still remember years ago when a well known guy in this industry first started imaging from DSW. He got a CDK14 and put it on a high-end mount with absolute encoders. He decided to run it unguided and he had nothing but trouble. Yes, he got a few decent subs but he threw out most of the data that he gathered. He only lasted a couple of weeks before he flew back out to the observatory and retrofitted a guider on the system. After that, the scope was useable. Lesson: Don't be that guy.
John
I can still remember years ago when a well known guy in this industry first started imaging from DSW. He got a CDK14 and put it on a high-end mount with absolute encoders. He decided to run it unguided and he had nothing but trouble. Yes, he got a few decent subs but he threw out most of the data that he gathered. He only lasted a couple of weeks before he flew back out to the observatory and retrofitted a guider on the system. After that, the scope was useable. Lesson: Don't be that guy.
John
Helpful Engaging
John Hayes:
The Celestron Edge14 has a good optical system but a very mediocre mechanical design. The primary can move and the entire OTA is not super rigid. You might get some useable results by imaging without guiding but why? Guiding is easy and it guarantees that you won't have guide errors due to mechanical flexure or thermal issues. Guiding will also greatly improve your image yield. High quality sky time is valuable so don't throw some of it away by not guiding!
I can still remember years ago when a well known guy in this industry first started imaging from DSW. He got a CDK14 and put it on a high-end mount with absolute encoders. He decided to run it unguided and he had nothing but trouble. Yes, he got a few decent subs but he threw out most of the data that he gathered. He only lasted a couple of weeks before he flew back out to the observatory and retrofitted a guider on the system. After that, the scope was useable. Lesson: Don't be that guy.
John
Thanks John - my understanding is that normal guiding won't work because of differential flexure problems. The alternative, which I know that you use, is the ONAG from Innovations Foresight which doesn't come cheap. If my ASA DDM 85 can succeed unguided then that would obviously be the best option - if not I guess I'll have to get the AMEX card out! I've got off axis guider that I could use, although past experience with a CX11 wasn't good as it struggled with finding a guide star.
Peter,
You could just use an OAG on the 14" as well. That's what most folks do with that scope.
John
You could just use an OAG on the 14" as well. That's what most folks do with that scope.
John
Well…. yes…. I have access to a CDK24 on a 10micron GM4000 (Astronomy Club). This year I started using it for imaging. Not going into my technical problems, but getting the first images out was work. At least now I am able to get pictures from it with 120s unguided. I would like to guide, but there might be a "backlash" issue with the mount (however, Baader told me that the 10m does not have a backlash?!?!?) and guiding kind of fails using PhD2 (maybe it is me not able to set up PhD2 properly using a 3960mm focal length and OAG)… So in short, yes, I get reasonable subs (120s) unguided, but not recommended. If technical issues are sorted I would definitely guide!
Rob
Rob
In the grand scheme of things the Innovations Foresight On Axis Guider fits in nicely with the expense expectations of an Edge 14 set up - definitely stay away from the reducer, which has many bad reviews BUT that's also the advise of one, John Hayes, and that's good enough advise all by itself! (I have one that's brand new and unopened and I'll be dumping it soon)
Seeing will be your biggest enemy in any case from my experience (from a bad Bortle 8 zone anyway).. It is, however, very rewarding when it all comes together! Long Focal Length is fantastic.
EDIT: I may have been too hasty in my condemnation of the reducer as others seem to be quite satisfied BUT I still don't plan to ever use mine if anyone needs one!?
Seeing will be your biggest enemy in any case from my experience (from a bad Bortle 8 zone anyway).. It is, however, very rewarding when it all comes together! Long Focal Length is fantastic.
EDIT: I may have been too hasty in my condemnation of the reducer as others seem to be quite satisfied BUT I still don't plan to ever use mine if anyone needs one!?
I don't find the reducer for my C14 Edge bad at all. I must have a good example. It produces good stars right to the field edge on the ASI2600 sensor. I don't use the ASI6200 on the reducer as field calibration begins to get a lot harder.
It is surprising how effective imaging deep sky objects is at F11 as well. I saw no issues with the trade off of having longer integration times. My first first light was at F11 and I was pretty much blown away at the extra detail seen from the increased image scale. However, I do favour the reducer as it helps mount equipment by moving all the connected devices away from the back plate of the C14- its weird shape can cause issues if you need to get devices close the back.
I use the ONAG on my C14, the mirror is locked with low profile mirror locks and I use the SMFS focus system. The SMFS, preserving the available back focus will allow me to fit a Falcon V2 rotator which will be fitted shortly to complete my system.
The OTA is held in the Paramount MX+ versa plate using Bisque rings which hold the OTA very rigidly.
I also find that using a CMOS camera I don't need very long exposures except for narrow band imaging so the aspiration of 20 minutes unguided, like a lot of others, I do question the need. If you can afford the outlay I would go for the ONAG- it really is a game changer especially at F11 where I believe guiding is a necessity and not something that can be negated in all circumstances.
The ONAG can eat up back focus as it has 66-68 mm used by itself alone but by careful adaptor selection with the camera and filter wheel I'm at 128 mm leaving me enough back focus to add a rotator whilst still staying at the suggested 146mm (which according to Gaston is somewhat flexible depending on camera and conditions).
It is surprising how effective imaging deep sky objects is at F11 as well. I saw no issues with the trade off of having longer integration times. My first first light was at F11 and I was pretty much blown away at the extra detail seen from the increased image scale. However, I do favour the reducer as it helps mount equipment by moving all the connected devices away from the back plate of the C14- its weird shape can cause issues if you need to get devices close the back.
I use the ONAG on my C14, the mirror is locked with low profile mirror locks and I use the SMFS focus system. The SMFS, preserving the available back focus will allow me to fit a Falcon V2 rotator which will be fitted shortly to complete my system.
The OTA is held in the Paramount MX+ versa plate using Bisque rings which hold the OTA very rigidly.
I also find that using a CMOS camera I don't need very long exposures except for narrow band imaging so the aspiration of 20 minutes unguided, like a lot of others, I do question the need. If you can afford the outlay I would go for the ONAG- it really is a game changer especially at F11 where I believe guiding is a necessity and not something that can be negated in all circumstances.
The ONAG can eat up back focus as it has 66-68 mm used by itself alone but by careful adaptor selection with the camera and filter wheel I'm at 128 mm leaving me enough back focus to add a rotator whilst still staying at the suggested 146mm (which according to Gaston is somewhat flexible depending on camera and conditions).
Helpful
Seung-Jun Kim:
I doubt if it is possible without AE.
Relative encoders (such as on Planewave mounts) can be just as good in terms of tracking, the only significant difference being initialization.
Well Written
You can use a different technique: exposure time for 1-2 seconds on a bright object, you will get several thousand images, stack these into packages with Autostakkert and edit them normally with Pixinsight. I have edited bright PNs in my gallery in this way.
https://pixlimit.com/techniques.html
cheers
Peter
Concise Supportive
John Hayes · Jul 22, 2025, 09:56 PM
The Celestron Edge14 has a good optical system but a very mediocre mechanical design. The primary can move and the entire OTA is not super rigid. You might get some useable results by imaging without guiding but why? Guiding is easy and it guarantees that you won't have guide errors due to mechanical flexure or thermal issues. Guiding will also greatly improve your image yield. High quality sky time is valuable so don't throw some of it away by not guiding!
I can still remember years ago when a well known guy in this industry first started imaging from DSW. He got a CDK14 and put it on a high-end mount with absolute encoders. He decided to run it unguided and he had nothing but trouble. Yes, he got a few decent subs but he threw out most of the data that he gathered. He only lasted a couple of weeks before he flew back out to the observatory and retrofitted a guider on the system. After that, the scope was useable. Lesson: Don't be that guy.
John
I honestly never understood why some insist on using unguided setups. I thought I maybe missing some advantage I was not aware of.
Ashraf AbuSara · Aug 26, 2025, 08:38 PM
John Hayes · Jul 22, 2025, 09:56 PM
The Celestron Edge14 has a good optical system but a very mediocre mechanical design. The primary can move and the entire OTA is not super rigid. You might get some useable results by imaging without guiding but why? Guiding is easy and it guarantees that you won't have guide errors due to mechanical flexure or thermal issues. Guiding will also greatly improve your image yield. High quality sky time is valuable so don't throw some of it away by not guiding!
I can still remember years ago when a well known guy in this industry first started imaging from DSW. He got a CDK14 and put it on a high-end mount with absolute encoders. He decided to run it unguided and he had nothing but trouble. Yes, he got a few decent subs but he threw out most of the data that he gathered. He only lasted a couple of weeks before he flew back out to the observatory and retrofitted a guider on the system. After that, the scope was useable. Lesson: Don't be that guy.
JohnI honestly never understood why some insist on using unguided setups. I thought I maybe missing some advantage I was not aware of.
With an SCT, I agree…just asking for trouble.
But with a solid scope on a solid mount, I definitely prefer unguided (with my Mach 2) for it’s simplicity and a few less things to go wrong. Almost no settling time after a dither. The unguided scope doesn’t care if clouds or a branch get in the way or you have bad seeing. Nina sequences are very efficient and predictable…no aborting. It will do exactly what you tell it to do until you tell it to do something else.
With my roll-out driveway setup, I just use the polar align scope and run a 15 minute or so dec arc model at dusk and then I can get 5 minute unguided images at about 1700mm with 3.76u pixels which works for my skies. If I were at a Bortle 1 site, I may think differently since I’d want longer subs.
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In my experience it depends on the OTA.
I had, now sold, a 9.25” EHD and I just could not get a decent pointing model with it.
So something obviously moved inside the scope.
But, a friend of mine gets APO-like models with his 9.25 EHD, so RMS < 8” or something like that.
Also, there’s a review somewhere on the internet of a use case with a GM2000 and C14 EHD running unguided.
So it is possible IF you have a solid OTA, so the lottery is real.
CS
Miguel
I have guided my C14 with a separate guide scope and tried imaging unguided. I found that any kind of guiding worked way better than going unguided. I have always thought that the idea of flexure is an overblown idea.