Upgrading my CCD Camera setup

[lazjen]

I've been lucky enough to get a bonus from work this year and so I'm thinking of getting a better CCD camera for my setup with a primary aim for creating better pretty astro images (DSO - nebula/galaxies). So, help me spend the money appropriately. :)

My current CCD is the Sbig ST-8XE. I intend keeping it and re-purposing it solely for photometry. I find the blooming to be a major inconvenience when doing imaging especially when doing the processing, since I also get star spikes as well. My other issue with it is the cooling. The max cooling it can manage is about 34 below ambient, which is not really good enough given the heat here in Brisbane in summer, so it doesn't reduce enough of the dark current noise.

For my system, I image at either 2000 mm (f7.9) or with a reducer at 1340 mm (f5.3). When I use the ST-8XE, that's 0.93"/pixel or 1.39"/pixel.

I've been looking at the new 16200 cameras around. The price (with all the extras I suspect I'll need like FW, filters, etc) is around my budget. It's the specs on the really low noise (<0.1e- for dark current) and probably 10 degree better cooling (so easier to achieve some lower temperatures without hard pushing on the system) that makes me interested.

However, I'm not sure if it's really a good match for my system. With the 16200, at 2000 mm, I'll be at 0.62"/pixel and for 1340 mm it's 0.92"/pixel. I'm not sure if this is good or bad (or better than my current setup), and my searches for info haven't enabled any enlightenment yet.

So, on to my questions:

1. Would a 16200 CCD camera be a good fit for my system (I'm leaning towards the Moravian at this time)? If not, what should I look at that would be a significant improvement over the ST-8XE?

2. I am thinking that given the size of the sensor in the 16200 (27.2 × 21.8 mm) that my current 1.25" filters will cause vignetting. Is this correct? If so, I'll need to get filters (LRGB, HA, OIII, SII) in 50mm - what brand(s) should I consider?

3. In my current setup, from the back of the focuser to the filter wheel, I'm at 2" (or is it 48 mm?) for the spacer/reducer diameter. I assume this is still ok? (I also have a 2.5" flattener that I can attach to the back of the focuser before dropping to 2" if needed).

I'm not in a rush to get a camera (besides the bonus doesn't get deposited until the end of the month :D ), so I'd like to hear any suggestions, questions, etc. that will help me make a better decision. Thanks for any help! :)

[RickS]

Would love to help :) My bonus is going into Super :sadeyes:



0.62"/pix sounds like a reasonable image scale for high resolution imaging. You'd need 2 arcsec seeing to take full advantage of the resolution (approx 3.3 times the image scale.) It won't be the fastest system but it won't be terrible. I was running a RC10 with a KAF-8300 for a while (5.4 um pixels) and I thought it worked pretty well. 0.92" would trade off some resolution for speed and give you some extra FOV.

How are you guiding? You'll probably struggle to get good results without an OAG at 0.62"/pix and a reflecting scope.



From an image scale POV it looks OK. I'd be concerned about the size of your image circle with a sensor that size. You'll probably need to use the flattener (and check the specs to see how well it will cover the sensor.)

Your reducer may struggle to present a large enough flat field for the sensor as well.

If you're willing to crop corners it may not be such a big deal.



Yep, you'll need bigger filters and may find you get a fair amount of vignetting even then. I like Astrodon filters but they are expensive.



You'll probably have to fiddle with spacing for the flattener to get the right distance to the sensor. You might also find you need to deal with tilt.

Another thought: the 16200 doesn't have the most fantastic read noise. You'll need to be prepared to do long subs in narrowband.

Here's another option to think about: a camera with a Sony ICX-694 sensor. With the reducer that would give you an image scale of 0.69 arcsec/pix. The ICX-694 is very low noise and has great QE. It's smaller so the image circle of the reducer is probably fine and you can use your existing filters. The only downside will be the smaller FOV...

Cheers,
Rick.

[lazjen]

I'm use to the system not being fast anyway.



Already using an OAG, no plans to change there.



I used the flattener with my DSLR - Canon 6D full frame and it worked well, so I think that should be ok?



That's possible. I think remember needing a slight crop with the 6D when using the reducer.



Of course. :) I'll review prices to see if I can fit them in budget. Maybe they might be a gradual acquisition instead of getting all at once.



What's likely to tilt?



What amount of time are we talking about here at a minimum? I've found you need a fair amount of time anyway to get narrowband data, that I've done up to 30 min subs. Probably the minimum I've effectively used is 5 min and that's just Ha.



A better QE to the 16200, dark current noise a little bit better than the 16200. The FOV is definitely not as nice (but I might be able to get over it :) ) and it's has under half the full well capacity (is this an issue?).

Would the Sony still be ok to use without the reducer if I want to use the full focal length?

[RickS]

My experience with a full frame sensor (KAI-11000M) on a RC10 wasn't that great (bad vignetting and field curvature) but if you got good results with a DSLR then hopefully you're OK...



The 3nm narrowband filters are particularly spendy but worth considering for Oiii. Helps a lot with light pollution and also provides some moon tolerance.



Large sensors are just less tolerant of any small amount of tilt wrt the image plane.




If you're used to 30 minute subs then you should be fine.



Dark current noise is rarely a major issue with CCD cameras. Read noise is the real enemy and the impact increases with the square of the RN. With low read noise you can do much shorter subs, hence shallower wells aren't a real problem.



That's an image scale of 0.46 arcsec/pixel. If you had great seeing and an AO unit it might be worth trying but for typical SE Qld seeing you'd be significantly oversampled.

Cheers,
Rick.

[Slawomir]

What about KAI 11002? If has higher read noise but also nice 9um pixels (higher sensitivity with the same set-up) and costs about the same as 16200...

[Somnium]

the low QE on that is not a problem ?

[RickS]

I have a STL11K if you want to try it, Chris. I'm personally a big fan of 9um pixels :)



A lot of great images have been taken with that sensor despite low QE. It's just one factor to consider.

[lazjen]

I think I've discounted the 11002 from my shortlist. It's obviously better than my current CCD, but I don't feel it's worth it as an upgrade. And as mentioned, the QE is not as good as the other chips mentioned.



So the ICX-694 has half the read noise of the 16200, so a quarter of the noise impact of the 16200? So in this case 1/4 quarter noise beats the half well capacity, I assume?

I've got a lot more reading/research to do I guess. At least with the ICX-694 I don't need to get any more filters for now. Just camera and filter wheel. Tempting. What brands are worth looking at for this chip? A quick search shows QHY, QSI, Atik, Starlight Xpress - any others?

[lazjen]

Well, 9um pixels is exactly what I've got now - so no arguments for me about it.

I'm tempted to try the STL11K - maybe when there's weather suitable for it's use, so late April or into May, maybe? :) I'll chat with you about it sometime.



There's definitely no silver bullet, that's for sure. :)

[RickS]

Yes, it takes 1/4 of the time to get a sky limited sub so the shallower wells aren't a problem. Hopefully, fewer wasted subs as well.



A FLI Microline would be lovely if you can afford it. There are a few folks around here with the ICX-694 in a SX camera. Mike Sidonio, Greg Bradley and Ray/Shiraz are the ones that come to mind.



NP. Just let me know when you're ready. The camera has been sitting in the Pelican case since I got my Apogee U16M.



True, alas. At least for any sane level of expenditure :lol:

[lazjen]

That's quite useful then, especially when there's variable weather around and I grab whatever subs I can in the small time windows.



I had a quick look this morning... certainly a premium price. I'll have to look at it more closely to see whether the extra cost is worth it over some of the other models.



Ok, will do.

[Slawomir]

I am well aware that I am biased, but QSI has better cooling than Atik and SX and also arguably has a lower read noise. FLI would be better still, but is more pricey. I really like the QSI WSG-8 combo, as it reduces the number of individual parts in the optical train and thus eliminates a few potential gremlins...

[rustigsmed]

exciting times deciding upon a new camera!
I am very happy with the qhy22, i decided to go it over the atik for the superior cooling (-45degs, 2 stage) - and was a bit cheaper than the trius. if i could have afforded a bit more i would have gone an integrated filter wheel system like Slawomir has suggested below.. as long as you can get all the filters you use in there!

[lazjen]

That QSI WSG-8 does look like a great combo, and comes well under the base price for the FLI. Add my existing filters and guide camera definitely makes it an easier solution overall.

*****

I like a lot of the aspects of the ICX-694, but being effectively forced to use a reducer, I'm thinking it's not going to be great for doing galaxies. Am I wrong to think this?

Maybe I need another scope... :)

[RickS]

Yes, you are wrong to think this :) The important thing is the image scale which is 0.69 arcsec/pixel. You won't get higher resolution than this in SE Qld except on occasional nights of exceptional seeing.

Take a look at some of Mike Sidonio's galaxy images. His focal length is less than yours would be with the reducer and he's using the ICX-694.

The only disadvantage of the 694 is its small size which is fine for typical galaxies but not so great for large nebulae.



Now you're talking. A fast refractor would complement the RC10 nicely.

Cheers,
Rick.

[lazjen]

I've got 7, so the 8 position wheel would do nicely. Not sure what I could get for the 8th filter if I went for that option.

Also, while it's sort of exciting times deciding on a new camera, I can tell you, it's starting to get to be more perplexing as I go along. :)

[Atmos]

You could get a Johnson V band filter for photometric studies or burn some cash and get a 3nm NII for kicks :)

[lazjen]

I actually have a set of 5 photometric filters that will be put into the ST-8XE's 5 position filter wheel. That's why I'll be keeping that camera.

I suspect the 8th slot would stay empty for a while. :)

[lazjen]

Ok, I understand. I've also found a few galaxy images around the same focal length I'd be at.



Could you point out some specific images? I've tried searching but I seem to turn up images using an FLI 16803, not an ICX-694.

[QUOTE=RickS;1235529]The only disadvantage of the 694 is its small size which is fine for typical galaxies but not so great for large nebulae.

Theoretically, I can solve the large nebulae with mosaics, so while it's not ideal, at least it's not impossible.



What am I looking for here? What budget do I need to get something to work with the ICX-694? Even with the fully configured QSI, I'd still have some budget left if I'm going to go further into the deep end. :)

[RickS]

Here are a few (you can pay me later, Mike).

http://www.pbase.com/strongmanmike2002/image/162566740
http://www.pbase.com/strongmanmike2002/image/162509024
http://www.pbase.com/strongmanmike2002/image/161079369
http://www.pbase.com/strongmanmike2002/image/162137991
http://www.pbase.com/strongmanmike2002/image/161585660



I'd go for a Tak but a small WO refractor and reducer or flattener would do the trick. Something 700mm FL or less would complement the big scope nicely.

[lazjen]

Thanks for the images. I see what you mean.



Those Tak prices :eyepop: And the price of the reducers!

And I just looked at the price of the WO refractor.

In both cases, I could probably scrap up enough to get the base scope - it's the extra bits that would kill.

Maybe I better keep an eye on the classifieds to see what turns up. :)

[lazjen]

Bit of an excavation for this thread, however for completeness I thought I'd update:

I've been able to borrow Rick's ST11K to try in my system. Unsuccessful, but informative. My focuser (moonlite) is too weak to hold it and my OAG causes vignetting. Doing a larger frame camera upgrade basically means buying everything from the camera to the back of the scope.

Unless I get some more information to change my mind, I think I'll hold off on any upgrades this year and reconsider my options next year - hopefully with an increased budget overall to expand those options.

[gregbradley]

A KAF8300 camera seems to be the go for the smaller lightweight scopes that does not put much pressure on the focuser etc. A QSI WSG8 is about the bees knees for them. Another may be the Moravian.

A KAF16200 is APS sized so about 3/4 of a 11002 but that may take the pressure off the focuser in terms of weight etc. Moravian sell one with a filter wheel and an OAG for about Euro $3400.

As far as read noise goes the KAF16200 is very low read noise compared to other Kodak sensors around 8 electrons for the Moravian and down to 6 for the FLI Microline version.

Other smaller sensors are all listed as variations on the QSI cameras - Sony ICX694 or 814, Kodak KAI4022 which is 15mm x 15mm and 7.4 micron pixels is a good performing sensor and smallish (square though).

If I had a small refractor like an FSQ106ED (expensive though) I would probably go with the KAF16200. Its the next u-beauty sensor that will take over from the KAF8300 in terms of popularity. 6 micron pixels matches a lot of people's telescopes and seeing. It will be a big hit.

Full frame sensors like KAI11002, KAI 29050, KAF16000, KAF16070 are all going to do require bigger focusers, field flatteners and stronger adapters otherwise you will get vignetting, coma in the corners and flexure.

Greg.

[glend]

I ASI1600 might suit your setup. Brand new, lots of good reports, low cost compared to the 8300, but far less noise and it is super sensitive. It uses a Panasonic chip and is likely to be the first of the next generation sCMOS cameras.

[gregbradley]

Sounds interesting Glen. Do you have a link to one of these?

Greg.

[lazjen]

Heh, that's what started this thread - it was what I was initially considering a change to from the ST-8XE.



Before I switched to CCD, I was using a full-frame DSLR (Canon 6D) and had sorted out the field flattener - still had some vignetting though, but it wasn't much.

However, the Canon 6D was very lightweight, much less than the monster cooled CCDs! So, yes, I'm not really surprised by needing a better focuser - it was more I had forgotten that I'd need it.



I've been reading some of the threads over on CloudyNights. It looks very interesting and quite promising. I'll be watching what comes of it all over the next few months.

The whole CMOS potential is another reason I'm not concerned about waiting for a while. It could be a significant disruptive change that might be worth jumping onboard. I'm hoping more choices become available too.

[lazjen]

It's the ZWO camera.

Check this link out: http://www.cloudynights.com/topic/535857-has-the-1200-large-chipped-asi-1600-made-existing-modestly-priced-ccds-obsolete/

It's a bit of a mega-thread now, but there's some pointers to info, etc.

Another link: http://www.cloudynights.com/topic/536494-m51-in-poor-seeing-20001s-asi1600mm-cool/#entry7205950

[rmuhlack]

http://www.iceinspace.com.au/forum/showthread.php?t=144427

this is the camera: https://astronomy-imaging-camera.com/products/asi-cooled-cameras/asi1600mm-cool/

[gregbradley]

Thanks Richard.

I read those threads and looked at the ZWO Website. A mono version of the Olympus OMD sensor. Sounds good overall. The few sample images were not though very good except for the M51 image which was quite good.

A bit early to comment but this may be more an alternative to cooled DSLR imaging.

When an APSc sized Sony Exmor R sensor or 35mm full frame mono CMOS sensor gets into one of these it could be very good. Imagine a mono version of the Sony A7s sensor?

Greg.

[Camelopardalis]

What may come from the CMOS world in the next few years is mind boggling. Whether Sony ever releases their large CMOS chips in mono versions to offset the death of their CCD business remains to be seen...they've so far not bothered beyond the 694-sized chips.

The ASI1600 is here and now. And bigger. With correct calibration, almost anyone who buys a 8300 over one of these is mad :P

[gregbradley]

It certainly has potential. I look forward to seeing some regular images taken with one. 1 second exposures and 40gigabytes of data to process sounds pretty arduous so 6 hours of 10minute subexposures or similar would be of more interest to me.

The QHY42 if its not just vapourware (their 16200 camera seems to be awfully slow being released) and if the price was lowish could be a hot item.

Greg.

[Camelopardalis]

Yeah I'd only be interested in taking "longer" shots, 5-10 minutes. But if that checks out OK then it's a game changer at around $2000.

Big fat pixels on a large chip are a whole other game :D

[lazjen]

I hope that both modes work well. I could see using the grab a lot of frames in a short period of time being useful when the season's weather isn't that great, e.g. like the extended summer we had this year in Brisbane.

Then in winter, when you can string a few nights together, do some "longer" shots.

Really looking forward to seeing some real results from this camera.