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Old 23-11-2014, 07:28 PM
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Amaranthus (Barry)
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QHY22 or Atik 460EX? Which to choose for Sony ICX694 sensor?

I'm interested in comments from users of these two cameras (monochrome, for both LRGB and NB):

Atik 460EX: http://www.atik-cameras.com/products/info/atik-460ex

QHY22: http://www.gamaelectronics.com.au/QHY21_22_23.html

For various reasons, I've settled on the Sony ICX694 as my sensor of choice for my CCD upgrade, and now I'm decided on the 'wrapping'. (I've ruled out the QSI 660 and Trius SX-694 for price and other reasons.)

I've read about some issues with the QHY22 connections (loose). But it cools to -45C below ambient (Atik goes to -25C or so), although I realise the ICX694 is not all that demanding on cooling. Atik software seems nicer but I don't really need it (happy with Nebulosity, APT, DSS and Startools). Both have good desiccant control, and are lightweight so won't be demanding on my focusers. The QHY is about $170 more than the Atik.

But actual user feedback, on these models specifically or QHY and Atik specifically, would be much appreciated!
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Old 23-11-2014, 07:38 PM
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Merlin66 (Ken)
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I use the ATiK314L for spectroscopy, but many others use the ATiK460.
It has been extensively tested by the spectroscopy guys (See Buil's noise measurements) and is recommended.
http://www.astrosurf.com/buil/isis/noise/result.htm
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Old 23-11-2014, 08:04 PM
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Amaranthus (Barry)
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Thanks Ken. On those results, both cameras do extremely well, although the QHY22 yields a slightly lower readout noise.
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Old 23-11-2014, 09:06 PM
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Have found with an f4 scope and the very small pixels of a 694 that you need the CCD to be precisely aligned with the optical focal plane. Not sure how the two chosen makers deal with it, but it is a big issue and probably worth asking them. Otherwise, as you say, cooling is not such a big deal with this chip - mine works fine at 0C.
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Old 23-11-2014, 09:09 PM
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Amaranthus (Barry)
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Ray, did you have problems with focal-plane alignment with your Trius SX-694 (after you got the Peltier issues sorted)? If so, what were the noticeable effects?

(I'm looking to use this with an 8" CF Newtonian at f/4, ED80T at f/4.8, a SW120 at f/4 and a C8 at f/6.3.)
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Old 23-11-2014, 09:22 PM
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Hi Barry. As first supplied the focal plane was a little bit out of plumb and needed slight tweaking. After the Peltier was replaced it was a long way out and I spent about 4 hours making up a jig and re-aligning it with a laser using the adjusting screws on the camera. The effects of the misalignment were dire - star shapes and sizes varied over the field of view. I think that, with a CC, image plane tilt can lead to under-correction of coma on one side of an image grading to over-correction on the other, as well as varying stars sizes due to focus shift. The adjustment mechanism on the SX is just good enough to get everything aligned to the required 20 or so microns, but the opposing screws are fairly small and the alignment can move if the camera is bumped at all - I presume that the Al housing threads give slightly.

Last edited by Shiraz; 23-11-2014 at 09:45 PM.
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Old 24-11-2014, 02:36 PM
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Interesting, thanks Ray (I guess this would be even more of a concern with the ICX814 sensor). Anyway, I have asked the suppliers!

Any other opinions out there, before I make a final decision?
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Old 30-11-2014, 03:50 PM
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So, update for those interested - I ended up going with the QHY22 (http://qhyccd.com/en/left/page2/qhy21-22/). For a few hundred $$ extra I got a two= rather than single-stage Peltier cooler (so down to -45C below ambient, rather than -25 for the Atik), anti-dew heater, a hard pelican case and a 240-12V adapter. I'm sure I would have been happy with either, but I think I made the right choice for me.

Now waiting for it to arrive, followed by the obligatory few weeks of cloud to follow! I also have an 8" f/4 newt astrograph about to order (FL = 800 mm) which will complement nicely my ED80T (FL = 384 mm at f/4.8) and my C8 (FL = 1280 mm at f/6.3).
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Old 06-12-2014, 07:34 AM
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Good choice Barry. The extra cooling is a good thing. Most CCD evils are fixed with powerful cooling so whilst it may be clean at warmer temps there are benefits to powerful cooling still. Long term CCD damage fades with powerful cooling as well as thermal noise of course. I used to notice a better image from my STL11 on cold nights when I cranked it to -35 over the usual -20 to -25C. Images were a bit crisper and cleaner that showed.

Greg.
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Old 06-12-2014, 03:39 PM
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Thanks Greg for the feedback - it supports my thinking. I should be able to keep the LRGB sub lengths fairly tight with this setup, and maximise my NB benefits. Overall, I was very impressed with the net benefits of the ICX694 sensor. It seems like it makes all the right compromises (given that no sensor is perfect) - at least for my setup and goals right now!
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Old 06-12-2014, 06:30 PM
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Yep, second that. An excellent choice.

There is perhaps only one other camera I would pick over the qhy22, and that is the microline 694.
FLI has managed to get the read out noise down to 3e- rms which is up there with professional science cameras with e2v chips. It's probably only worth the extra if you were seriously in to deep, narrow band imaging.
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Old 07-12-2014, 12:30 AM
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Microline 694 would be the go but its twice the price. You get the best CCD window, argon, a nice shutter (694 has an electronic shutter though), powerful cooling and higher grade electronics.

Perhaps the next gen Sony chips may be even more interesting especially if they make them a bit bigger and ideally deeper wells.

Greg.
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Old 07-12-2014, 08:54 AM
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Amaranthus (Barry)
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Hah, if I ever accumulate the bucks, I might consider an FLI for my first full frame CCD! For the next few years, I'll push the QHY to its full extent
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Old 07-12-2014, 09:01 AM
clive milne
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The problem with Sony is that they primarily focused on the consumer market. Terry Platt (amongst others) regularly try to convey a sense of demand to Sony wrt a larger version of the 694 chip. As Terry puts it, Sony work in quantities of millions so it simply won't interest them until they find a bigger market for it.

fwiw) the shutter on the microline is optional (and arguably redundant with a 694 chip)

It would be an interesting exercise to see how low you could get the noise on this camera by slowing down the digitization and using liquid cooling. For the average imager it would be a waste of effort, but it could be useful, perhaps even ground breaking in one specific niche.

Regards
C

Last edited by clive milne; 07-12-2014 at 09:13 AM.
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Old 17-03-2015, 11:18 AM
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Amaranthus (Barry)
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So, for various reasons I've not had much chance to try out my beautiful new QHY22 CCD, except for calibration testing in my man cave. Last night, at last, I got it all set up and did some experimental shots out under the dark Tassie skies.

The image below of NGC 2070 is the result of only 10 x 5 min subs (median stacked) in H-alpha, imaged with an ED80T. The camera was cooled to -40C, and I subtracted bias but took no darks or flats. The mount was polar aligned only with my polar scope, and I didn't activate tracking (hence the short NB subs!) -- there were lots of other priorities to sort out, and this was almost an afterthought. Still, the result was pleasing enough to tell me that I'm REALLY going to love this camera, especially when I start to go deep (and guided) with my integration!
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