Struggling to decide which ccd to go for!

[Jonk]

I've decided I'm ready for the step from dslr to ccd and have read everything I can find, including the thoughts and advice from the best this forum has and I still can't decide!!

I will be able to push £2k (new kit),taking into account a filter wheel and entry level rgb and eventually narrowband filters (more cost).

I'm well aware of the fov, resolution and sensitivity points, like well depth, pixel size etc. but one thing bugs me - cooling!

Some say that cooling isn't that important, but I can't help but think the cooler the better.

I'm trying to decide between an 8300 chip, like the Atik 383 and 694 chip, like Atik 460.

The 383 is larger, has better cooling but is noisier but the 694 is cleaner. I'm also really put off by a mechanical shutter on the 383.

Is cooling a major decision factor?

Is it more important for hot pixel noise or dark?

I am happy to produce a dark library and understand dark frames may be needed on the 383 but probably not on the 694.

I'll start with a 150 reflector for now and hope to get star71 or gt81 later on for wider work.

Long long, longer term I hope to get a long fl rc on a permanent pier, but that's when larger pixels are needed and a new mortgage, I mean camera!

Minefield!

Can someone please send me the answer. Thanks!!

[Davey-T]

After much pondering I bought the QSI683 a few months ago but because of the weather I've had about 2 hours use so far so couldn't give much of a review. 

Had my old Atik 314L since they first came out and it has done sterling work on the 10"SCT.

Will put more thought into it tomorrow

Dave

[Merlin66]

http://astronomy-imaging-camera.com/product-detail/asi174mc-and-asi174mm/

The new cooled CMOS ASI174MM with shutter exposure to >16min may be of interest.

Functions as a "normal" fast frame 1/1000sec AVI camera as well - good for the Sun/ Moon and planets.

[Jonk]

I've just scanned this page:

http://www.starrywonders.com/coolinghidden.html

It's not that conclusive, but seems to point to cooling to maximum is not necessarily required.

I'm leaning towards the 694 (Atik 460 most likely) as only during the peak of summer it'll be 20 degrees or so in the night. Cooling down to around 0 degrees will hopefully be enough to mitigate dark noise.

If not, then darks may be needed. No big deal.

I suppose I should just concentrate on the imaging skills and enjoyment rather than specs.

[swag72]

Here's a thought based on nothing more than my experience with the Atik 460, QSI690 and QSI683.......

Do not believe everything you read on the internet about the Kodak sensor being out of date and bad for calibration. I listened to this and hungrily devoured all the interweb snippets of information and came to the conclusion that there was no way I was going to get a 8300 chip. It was insensitive, it needed calibration frames ...... I probably found other things too. So I went for the Sony chip...... twice ....... because I believed the twaddle, Oh how I wish I hadn't.... I was resigned to mosaics for my life.

Then a stroke of luck - I found that the Sony chip actually BENEFITTED from darks...... so that was advantage number one gone then! 

After that, I looked long and hard at things and decided that it boiled down to one thing and one thing only................. Field of view. The Kodak FOV is lovely when compared to the Sony. I regret not getting one sooner.

My advise would be to do your homework based purely on targets, and field of view. If the Kodak suits you better then do it. Also, if you get a 8300 sensor camera with the integrated filter wheel aka QSI or Moravian you can still use 1.25" filters .......... Hurrah!!!!

[CSM]

My understanding is that it is more important to have the darks at the same temperature as the lights than to worry about making it as cold as possible.

[nmoushon]

I will echo Sara's advice and say that you really should have your top priority for your camera be the FoV. For me my main interest is galaxies and PNs which are very small targets so I will not be as restricted by FoV as much, especially with imaging at long FL. If you are aiming to image nebulae and have a shorter FoV then you might want to look at a larger chip size. You can play around in Stellarium with camera/scope combos and see what FoV you will get.

After that, and in a very close second (again targets play a big factor), is read noise. Since both cameras cool you are really only judging if the extra bit of cooling will help not really cooling vs no cooling. Unless you are always imaging in a very warm climate I would not think the extra -10C cooling will make that much difference in the end. Especially if one camera is already much less noisier than the other. 

I actually like Merlin66 suggestion a lot. That ASI 174MM cooled is actually on my short list of cameras to get. I would seriously consider it depending on what your targets are going to be. I started a thread based on my discovery of this camera and its uses for DSO imaging here: http://stargazerslounge.com/topic/258114-short-exposure-dso-imaging/  There are several links in the first post to images taken with the same brand of camera but different model. The last link in the first post is actually about this specific cooled 174MM and though it is new to the market is showing some very very good promise. Its very low read noise and high QE% really make up for it being a CMOS chip instead of a CCD. 

[Jonk]

Sara, you're one of the people I referred to when I said "advice from the best this forum has", so I will read very carefully and take notice of what you say.

The fact you chose the Sony chip, twice and still ended up at the conclusion that chip size is all important for target size and FL, has swung my decision back towards the 8300 as the one to go for (and also at my current spending limit).

It still bothers me about the mechanical shutter however, but I suppose there's no 'perfect' solution, there will always be caveats.

The QSI 683 is looking like a good option, as 1.25" filters can be used (cheaper being the main advantage).

I'll ponder some more, either choice I should get good results with, but the problem with me and a lot of others, is the desire to squeeze every last piece of performance out of the kit!

[perfrej]

The mechanical shutters are non-issues. They're usually good for zillions of exposures and I have yet to see one fail. I will also use this opportunity to second Sara's field of view notion. Besides that, I use two 8300-based cameras and never use darks. Noise goes away nicely in rejection stacking, so not a problem really.

Another point in favor of the 8300 over the Sony chips is the pixel size. The 5.4um pixels are perfectly adapted to the one metre range of focal length, so from 500mm or so (less if you want to stretch it) up to, say, 1400mm is good. If you want to do deep galaxy stuff at longer focal lengths you need larger pixels, which puts you in KAI-11000, KAF-16803 and KAF-16200 territory. The notion of a smaller Sony chip matching a longer focal length scope for galaxies is a bit on the steep side.

So, look at the field of view and the image scale (arc-seconds per pixel). The latter should not be much below 1 unless you have high altitude New Mexico style conditions, and not too much above 2 if you want nice stars. Naturally, it is OK to venture a bit outside of these general guidelines.

Kodak it is...

/per

[Jonk]

Thanks Per for that image! Kodak it is then, no ifs, no buts!

Seriously though, I understand larger pixels for longer FL, but in the future, a long way into the future, I hope to build up my equipment and have a long FL RC, with a large pixelled camera.

My ultimate aim is 2 fixed piers, one with short frac for wide, 1 with long RC for galaxies, then a roll out large dob for visual.

And no, I'm not loaded!

[swag72]

A good decision and one I am sure that you wont regret

[Jonk]

I do hope so, I don't like buying the wrong thing, I'd rather try and get it right first time.

The next question....

Atik, Moravian, QHY, SBIG, SX?!!!!

[ChrisLX200]

I do hope so, I don't like buying the wrong thing, I'd rather try and get it right first time.

The next question....

Atik, Moravian, QHY, SBIG, SX?!!!!

Either Atik or SX - mainly for UK support. Not that you won't get support from the others but it might be a bit more long-winded procedure.

I was going to stir the pot and suggest Sony is still an option, but I won't bother now... ;-)

ChrisH

[swag72]

Here's the thing.

I've had Atiks and their cooling was abysmal...... In the summer I struggled to get to zero degrees, but then I am out in Spain. The QSi cooling I have is brilliant.

The QSI and Moravians will allow you to use the 1.25" filters if you have an integrated wheel. 

If there's an issue my QSI had to go back to the US - A major balls ache. 

Make of that what you will Swings and roundabouts there's always compromises to be had.

[Jonk]

Ha yes it is still an option - I like the sensitivity and lower read noise the sony has to offer, but I have been convinced that fov is key.

If the best imagers on this forum have all chipped in to agree this, then I would be silly not to take the advice.

[Jonk]

Sara - does your QSI have microlenses?

I've read elsewhere they can cause diffraction spikes?

[swag72]

Sara - does your QSI have microlenses?

I've read elsewhere they can cause diffraction spikes?

I have no idea!!! Sorry! 

[ChrisLX200]

Ha yes it is still an option - I like the sensitivity and lower read noise the sony has to offer, but I have been convinced that fov is key.

If the best imagers on this forum have all chipped in to agree this, then I would be silly not to take the advice.

LOL! don't let them push you into a corner ;-)  Both Per and Sara routinely use 30min subs with their 3800 sensors (correct me if I'm wrong guys!), I used 15-20min subs with a 490EX and probably got the same depth. That is the higher QE working in your favour. If you have a good mount that extra length won't make any difference, however if your mount struggles a bit with long exposures then it just might... I've now got myself a Kodak sensor camera and realise I really have to go to 30min subs minimum, it's not a problem for me but I believe I can see the difference in sensitivity in the results. Don't get me wrong, either Kodak or Sony will work well for you to capture images, and all things being equal you'd be stupid not to go for the larger sensor.  Sadly all things are not equal so we make a compromise.

I just know I'm going to regret getting into this...: -).

ChrisH

[Davey-T]

If there's an issue my QSI had to go back to the US - A major balls ache. 

There is now a facility in the UK  for QSI repairs

No idea about the microlenses, some discussion I seem to recall about what appeared to leaking wells overflowing, used to be a common problem in the early days, not something that should be able to happen with modern CCDs

As per Sara, even in the UK I've had problems getting my Atiks down to -5 in the summer, QSI sails down to -20 no problem

Dave

[carastro]

I have to say my experience is the opposite to Sara's. 

I found the Kodak chip in my Atik383L very noisy compared to the Sony chip on my Atik314, and contrary to what Per said 

The mechanical shutters are non-issues. They're usually good for zillions of exposures and I have yet to see one fail.

 My mechanical shutter caused me a lot of problems.  It used to stick every so often and I'd lose the corner of a sub, it got worse and worse until I had to have it repaired.  I also found the flats a real fag having to take longer ones to avoid the shutter.

Maybe my Atik383 was an old one ( I bought it second hand) and why I had problems, I can only compare two different cameras that I was using during the same period of time.

Carole 

[ChrisLX200]

I have no idea!!! Sorry! 

Sara - does your QSI have microlenses?

I've read elsewhere they can cause diffraction spikes?

I have no idea either, but consider all the images on the net taken using a 383 + refractor, do you see any evidence of diffraction spikes? Nope :-)  I think it's a non-issue myself.

ChrisH

[Jonk]

It was only on 1 website I was reading earlier that this was discussed Chris with examples shown, but I can't find it now.

The QHY9s looks good spec wise, -50 degrees, heated window, fully sealed, ABG, good price with filter wheel - yet no-one has voted for this, any particular reason why?

[ChrisLX200]

It was only on 1 website I was reading earlier that this was discussed Chris with examples shown, but I can't find it now.

The QHY9s looks good spec wise, -50 degrees, heated window, fully sealed, ABG, good price with filter wheel - yet no-one has voted for this, any particular reason why?

No reason at all, folk tend to recommend those cameras they are using themselves or see being used successfully, there are probably not as many QHY9s 's in circulation. Looks good spec to me ;-) (Bern at Modern Astronomy listed it).

ChrisH

[Oddsocks]

Sara - does your QSI have microlenses?

I've read elsewhere they can cause diffraction spikes?

The KAF 8300 CCD and all the SONY Exview Super HAD CCD I/II versions used in main stream astro cameras use micro lenses. The overalll QE would drop to well below 50% without them.

[Jonk]

I've found the following test results: http://astrofotky.cz/CCD_Camera_Measurements_v2_2013-08-26.ods

Is it worth getting too hung up on tables like this, as we obviously don't know the test conditions, repeatability, measurement techniques etc.?

On the face of it, the QHY and Moravian cameras appear better for read noise at certain temperatures, but Atik and QSI are immensely popular, so I wonder why.

is it likely to be purely cost and support or is there more to it?

Is it a brand snobbery thing?

I suppose what I'm asking, those with Atik, why Atik, those with QSI, why QSI etc...?