Upgrading my CCD Camera setup

[lazjen (Chris)]

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 ), so I'd like to hear any suggestions, questions, etc. that will help me make a better decision. Thanks for any help!

[RickS (Rick)]

Originally Posted by 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.

Would love to help My bonus is going into Super

Originally Posted by lazjen

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)

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.

Originally Posted by lazjen

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?

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.

Originally Posted by lazjen

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?

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.

Originally Posted by lazjen

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).

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 (Chris)]

Originally Posted by RickS

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.

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

Originally Posted by RickS

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

Already using an OAG, no plans to change there.

Originally Posted by RickS

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.)

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

Originally Posted by RickS

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.

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

Originally Posted by RickS

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.

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.

Originally Posted by RickS

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.

What's likely to tilt?

Originally Posted by RickS

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

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.

Originally Posted by RickS

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...

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 (Rick)]

Originally Posted by lazjen

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

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...

Originally Posted by lazjen

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.

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

Originally Posted by lazjen

What's likely to tilt?

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

Originally Posted by lazjen

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.

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

Originally Posted by lazjen

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?).

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.

Originally Posted by lazjen

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

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 (Suavi)]

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 (Aidan)]

Originally Posted by 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...

the low QE on that is not a problem ?

[RickS (Rick)]

Originally Posted by 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...

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

Originally Posted by Somnium

the low QE on that is not a problem ?

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

[lazjen (Chris)]

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.

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.

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 (Chris)]

Originally Posted by RickS

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

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.

Originally Posted by RickS

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

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

[RickS (Rick)]

Originally Posted by lazjen

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?

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.

Originally Posted by lazjen

What brands are worth looking at for this chip? A quick search shows QHY, QSI, Atik, Starlight Xpress - any others?

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.

Originally Posted by lazjen

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.

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

Originally Posted by lazjen

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

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

[lazjen (Chris)]

Originally Posted by 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.

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

Originally Posted by RickS

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.

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.

Originally Posted by RickS

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

Ok, will do.

[Slawomir (Suavi)]

Originally Posted by lazjen

What brands are worth looking at for this chip? A quick search shows QHY, QSI, Atik, Starlight Xpress - any others?

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 (Russell)]

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 (Chris)]

Originally Posted by 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...

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 (Rick)]

Originally Posted by lazjen

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?

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.

Originally Posted by lazjen

Maybe I need another scope...

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

Cheers,
Rick.

[lazjen (Chris)]

Originally Posted by 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!

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 (Colin)]

Originally Posted by 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.

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

[lazjen (Chris)]

Originally Posted by Atmos

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

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 (Chris)]

Originally Posted by 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.

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

Originally Posted by RickS

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.

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.

Originally Posted by RickS

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

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 (Rick)]

Originally Posted by lazjen

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.

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

Originally Posted by lazjen

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.

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.