Monochrome camera selection for an 80mm Apo triplet - Forums

Topic starter

Jul 2, 2021

I currently have a ZWO 2600MM Pro on my C11" EdgeHD and a ZWO ASI2600MC on a Stellarvue 80mm Apo triplet which I have piggybacked on the C11 in my observatory. However, given I am now under Bortle 7 skies (it was B6 until recently), I've decided to stick primarily with NB imaging with few exceptions. The 2600MM is excellent and will remain but I want to add a second MM camera to the 80mm as the use of the 2600MC is become more of a rare event. In addition, my scopes are on a pier which is roughly 10 ft off of the observatory floor so simply climbing up to swap the cameras with each specific setup is not practical. Thus, leading to my question of best options for a second monochrome camera. So, do I:

just buy a second 2600mm for the 80mm?
get a 6200mm for the C11" and place my 2600mm on the 80mm?
think about a smaller pixel camera for the 80mm like the ASI183mm?
something else I have not thought about?

Any suggestions based on individual experience would be appreciated.

Bruce

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Björn Arnold

Jul 2, 2021 · Edited: Jul 2, 2021

Hi Bruce,

I would strike option 3. I've got this sensor on different systems. It's pixel size is just too small and the price is a 1-inch sensor. The 3.76um of the cameras you mention, considering the diffraction limit, are a much better fit and giving you a larger FOV without loosing detail. I'm perfectly ok with my camera only that on the small APO, I'd like the sensor a bit larger.

Actually, I'd place an idea under option 4 and suggest the following: bring your 2600MM at the APO and buy a CMOS/CCD with much larger pixels. I just assume you're not having the same seeing as in Chile.
What FL are you running your C11 on? Even if you are using it at f/7, you could buy a camera with 7um full-frame CCD sensor. (Would give you a image scale of 0,78"pp).

That's my opinion on it.

Cheers!

Björn

EDIT: PS: I'm sorry but I should have stated that I only had DSO imaging in mind when thinking about a suggestion.

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Bruce Donzanti

Topic starter

Jul 2, 2021

Thanks for your input, Bjorn. I am shocked you don't think I get seeing in central Florida as good as in Chile- LOL!

My FL on the C11 is 1960 (using the .7x reducer) and you are correct that DSO imaging is the main purpose.

I'll start exploring other options- thanks much, again.

DanRossi

Jul 2, 2021

The ASI294MM may be interesting to consider. In its unlocked Bin1x1 mode its pixels are even smaller than the 183MM with similar specs to the 183MM. In native Bin2x2 mode you'd be undersampled but can take advantage of the native specs and drizzle. It's larger pixels in 2x2 means it can also be used on longer focal lengths, so it can be versatile.

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denniswho

Aug 13, 2021 · Edited: Aug 13, 2021

Hi Bruce, I also have a stellervue 80 and I am running a 6200mm on it, and that camera is perfectly matched to that scope for both resolution and FOV. I just got a 9.25 so I have a very similar situation as you. I am leaning toward the ZWO 294mm for the 9.25 because of the native 4.63 (approximate) pixel size. Gary Imm uses the 294 on a C11 with superb results. I am also looking for a 2600mc for my Tak 60 grab and go.
Good luck
Dennis

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Nadir Astro

Aug 13, 2021

I would also go with 6200MM on 80 APO for greater FOV and large targets.

Bruce Donzanti

Topic starter

Aug 13, 2021

Hi Bruce, I also have a stellervue 80 and I am running a 6200mm on it, and that camera is a perfectly matched to that scope for both resolution and FOV. I just got a 9.25 so I have a very similar situation as you. I am leaning toward the ZWO 294mm for the 9.25 because of the native 4.63 (approximate) pixel size. Gary Imm uses the 294 on a C11 with superb results. I am also looking for a 2600mc for my Tak 60 grab and go.
Good luck
Dennis

Thanks for the feedback, Dennis. I know Gary and I had the 294 but sold it to help buy both versions of the 2600. The 294 is excellent with the larger pixels on the bigger SCTs and it produces great images. I regret selling it but the 2600 is slightly better in my opinion. I'll consider the 6200 for the 80mm.

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Bruce Donzanti

Topic starter

Aug 13, 2021

Nadir Astro:
I would also go with 6200MM on 80 APO for greater FOV and large targets.

Thanks for the feedback, Nadir. The 6200 seems to be a popular choice and one I need to seriously consider.

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Brian Meyerberg

Aug 14, 2021

I had an 80mm and I used an Altair 18. I would use the Asi2600 or 6200 with a 3.76 pixel size. Perfect combination and those cameras don’t have any amp glow.

seanhagerty

Aug 17, 2021

I put a 6200mm on my WO GT81mm I love the wide field of view. No regrets on that purchase.

Bruce Donzanti

Topic starter

Aug 30, 2021

Hi Bruce, I also have a stellervue 80 and I am running a 6200mm on it, and that camera is perfectly matched to that scope for both resolution and FOV. I just got a 9.25 so I have a very similar situation as you. I am leaning toward the ZWO 294mm for the 9.25 because of the native 4.63 (approximate) pixel size. Gary Imm uses the 294 on a C11 with superb results. I am also looking for a 2600mc for my Tak 60 grab and go.
Good luck
Dennis

Hi Dennis

Have you had any issue with tilt using the 6200 on the Stellarvue 80mm causing star elongation in a corner of the image?

I am very familiar with the 294mm and also Gary’s stuff. I used that camera on both the C11 and 80mm. It is an excellent camera but the 2600 is a cut above.

Bruce Donzanti

Topic starter

Aug 30, 2021

I put a 6200mm on my WO GT81mm I love the wide field of view. No regrets on that purchase.

Hi Sean

Any issues with elongated stars in the corner due to camera tilt? A number of folks have reported this.

Kevin Morefield

IOTD Staff

Aug 30, 2021

Bruce,

The diffraction limit in the Green channel at 80mm is about 1.75". You didn't mention the FL of the 80mm scope but If the FL is 450mm the image scale with your 2600 would be 1.72". So smaller pixels would not produce any more resolution. If the FL is more than 450mm the image scale gets smaller and so still no advantage. Assuming the FL were lower than 450mm, you might get some benefit from smaller pixels but I would think that all of the other parts of the decision such as QE, read noise, bit depth, cost, etc. would be far more important than any theoretical improvements in resolution that close to the diffraction limit.

Here's chart I did for a presentation a while back. This gives the diffraction limit for there different wavelengths. Quite a difference for the different colors at small apertures.

Kevin

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Bruce Donzanti

Topic starter

Aug 30, 2021

Thanks for the info and chart, Kevin. The Stellarvue has a 480mm FL (f/6) which gives it an image scale of 1.54" with the 2600 (I believe). While the pixel size of the ASI2600 vs. the ASI6200 is the same (3.76), the main interest is in the much larger FOV (APS-C vs. full frame). While that is appealing, the reported incidences of camera tilt issues with the 6200 has me a little concerned and not sure it is worth it.

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Kevin Morefield

IOTD Staff

Aug 30, 2021

Bruce Donzanti:
Thanks for the info and chart, Kevin. The Stellarvue has a 480mm FL (f/6) which gives it an image scale of 1.54" with the 2600 (I believe). While the pixel size of the ASI2600 vs. the ASI6200 is the same (3.76), the main interest is in the much larger FOV (APS-C vs. full frame). While that is appealing, the reported incidences of camera tilt issues with the 6200 has me a little concerned and not sure it is worth it.

If the increased cost of the Camera, FW, Filters, and a larger OAG don't bother you, a 6200 is a great choice. As long as your flattener will cover it, the tilt issues are solvable. I use a QHY600M with my FSQ106, and while the Tak covers full frame by a larger margin, there were tilt issues to solve for sure. The QHY uses a dovetail ring to attach the camera so I was able to shim camera using folded aluminum foil. I used CCDInspector as my guide, I shimmed, and tested iterating till I got it right.

I have seen this done with a metal foil tape which would be much better than what I did because my foil will move around if I dismount the camera.

I also use a QHY600M on my long FL CDK14 at F7. I didn't do any remediation on tilt with that setup.

Kevin

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seanhagerty

Sep 4, 2021

I have something going on in the corners. Not sure if its tilt or backfocus….still playing with it.

Jonny Bravo

Sep 4, 2021

I'm quite happy with my ASI294MM Pro and 0.8x reduced GT81 combo. Running it in the "unlocked" (i.e. bin1) mode, I get an image scale of 1.25". I do admit a bit of sensor envy when I look at the 2600 and 6200, though

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Bruce Donzanti

Topic starter

Sep 4, 2021 · Edited: Sep 5, 2021

I'm quite happy with my ASI294MM Pro and 0.8x reduced GT81 combo. Running it in the "unlocked" (i.e. bin1) mode, I get an image scale of 1.25". I do admit a bit of sensor envy when I look at the 2600 and 6200, though .

Well- I had the ASI294MM and sold it to a friend...and frankly, I regret it. I used it before and after ZWO "unlocked" it and I truly loved the camera but I got sucked into getting the 2600MM of which I have no regrets at all. It is a superb camera but I always get sucked into the "next" great camera which is why I am keeping my 2600MM on my C11" and thinking of adding the 6200 to my 80mm. But I need to think this one over a bit more before pulling the trigger.

Bruce Donzanti

Topic starter

Sep 11, 2021

Well- based on all of the advice, I pulled the trigger and bought the ZWO ASI6200MM pro. Hope to get some clear nights to test it out.

Thanks all.