I'm at a crossroads and undecided

[Carole]

I realise I am not going to get much further with the drawbacks of a DSLR.  I bought a DSLR coolbox last year but for a variety of reasons this has not proved to be satisfactory for me and it only cools to about 8 degrees below ambient.

As you know I bought an Atik 314L mono earlier in the year and decided to sell it.  I felt having to do several nights imaging to get one coloured image was too much faff, but additionally I was rather disappointed with the FOV being used to that of a DSLR.

I want to get myself a Cooled CCD with a larger FOV but am undecided which route to go down and would value some advice.

I am currently looking at the QHYL8 (cheaper option than an Atik) but I gather you don't get a lot of support with this, plus the capture software is unknown to me and I'm not exactly a whizz with adapting to new software.

Or the Atik383L - a lot more expensive but I am familiar with the software and support is better.

I was thinking of going for the OSC so I don't have the filter faffing, but every-one says they are less sensitive.  

I was quite taken with the idea of adding Ha to RGB images (which I did recently with the horsehead done on my DSLR heavily cropped and the Atik314L).

to be continued:

[Carole]

So currently I am thinking:

1. Do I go for the Mono and add Ha to DSLR images for colour (which I won't have to crop so heavily as with the Atik314L), apparently you can blur the colour image to "rub out the noise" and use the ha for detail.
I have to add I am not a fan of Mono imaging, so would want to produce colour.  

2. Do I go for a OSC which will be cheaper and saves the colour filter faffing, and try to use an Ha filter on this anyway.  

If I go for option 1 it does give me the option to later go onto narrowband and RGB filters but then I have the faff factor and a lot of extra expense.  If I go for option 2, I don't have the narrowband option and I think I am talking myself into option 1 but hoping I don't regret it - AGAIN!!

Either way, do you have any opinions of the QHY8L or the Atik383L bearing in mind the difference in price.  

I do already have a 2" screw on Ha filter which I am planning to use on the DSLR (for the time being).  

Thanks

Carole

[mickw]

So option 1 is that you buy a cooled CCD camera just to take Ha so you can add it to your DSLR images 

If you're not going to be doing narrowband stuff "ever" get option 2 a OSC and take Ha as you would with the DSLR

If you went for mono and you got a motorised filter wheel, you could set it all running and still go to bed

[Carole]

Just seen a Mono Atik383L second hand for sale.

Decisions, decisions.......

B....... it's gone.

Carole

[Mike]

Some of the OSC cameras still have good Ha sensitivity and can be used with Ha filters. The QHY8 is one that springs to mind. If you dont want the trouble of filters then get a OSC. Alternatively spend a bit more and get a mono camera and a motorised filter wheel. That way it can all be done automatically for you.

[MarkS]

Whichever way you go, (One-Shot-Colour or Mono) you will end up with the following advantages:
1) A chip with better sensivity than a modded DSLR
2) Almost non-existent thermal noise even in mid-summer
3) No "Canon banding" problem

Without doubt, a mono camera is far more versatile because various filters (narrowband and broad spectrum) can be used.  If you prefer colour imaging, then ironically LRGB from a mono camera is actually superior to the colour image from an equivalent OSC (for the same total imaging time). In addition, H-alpha from a mono camera is far superior to that from a OSC because all pixels are being used - not just the red ones.

If you choose mono, definitely get a motorised filter wheel with a set of compatible filters where refocusing between filters is not necessary so you can pre-program your acquisition without manual intervention.

In the OAS, most imagers seem to have opted for mono Kodak KAF8300 based cameras.  I think this indicates that this particular chip offers a good compromise between chip size, quality and price at the present time.

Certainly an OSC is easier to use but you do pay a penalty in terms of reduced versatility.

[Rocket Pooch]

Hi Carole,

If I was to buy a camera today I would buy one of these, well a camera with this chip in it anyway http://www.sxccd.com/sxvr-h694

If QSI used this chip I'd get another QSI, they seem expensive, but they a) work b) filters go into the box and lastly c) the cooling works properly. 

Chris

[JohnP]

If you choose mono, definitely get a motorised filter wheel with a set of compatible filters where refocusing between filters is not necessary so you can pre-program your acquisition without manual intervention.

Mark - Are you sure that refocussing is not necessary...? I would say that even with par focal filters & motorized wheel refocussing would be necessary due to mechanical tolerances etc. I know my RGB filters are meant to be par focal but there is no way I can do RGB without refocussing in between. I think investment in motorized (auto) focus unit would also be needed....

[Fay]

i would always have to refocus mine as well, also what about the flats? they have to be done for each filter

[RobertM]

Carole,

I would agree with Chris.  If QSI brought out a QSI694 then it would be a killer but alas there is not that much chance since the company are fairly wed to Kodak sensors (I did ask).  If you can get a second hand QSI 583 for less than £1800 then it would certainly be worth it for the convenience and save you money through cheaper (smaller) filters - you have to think of the package cost not just the camera !!!  The disadvantage of the Kodak 8300 chip (as used in the QSI 583) is that it does not have what's called a global shutter ie. it has to be used with a mechanical shutter.  That means flat frames can be an issue as the minimum exposure for the the mechanics  still means a very dim light must be used to do the flats (daylight is way way too bright).  The 694 sony chip has a global shutter so exposure times can be down to 1ms - no issues doing flats in bright light (with a eps panel for example)

The chip used in the SXV-M25/QHY8 also uses a global shutter so flats are easy but as Mark mentioned Ha would only use the red pixels (every fourth).  They would certainly be much better than a cooled DSLR but not as good as a mono camera.  Another thing you might want to consider is that with a OSC camera you will be capturing all wavelengths at the same time so if the session was interrupted by cloud then you already have RGB whereas for a mono camera (unless the filters are exactly par-focal) you may end up with a colour missing.

Don't expect a completely noise free camera when the outside temperature is  20 degrees celsius!  Most of the cameras you could afford only have 25 degrees of cooling but even that will be luxury compared with a DSLR

Robert

[Carole]

Thanks for your replies every-one, that gives me something to think about.  I am away and using some-one else's PC at the moment so don't have a lot of time to "research" chips.  I see the Atik383L does have the Kodak chip that Mark mentioned, but the Flats issue is something else to think about.

I don't think I am in the market for a QSI and I would have to be extremely lucky for a 2nd hand one to come along at that price.  

My current thinking is get a Mono CCD with similar size chip to the DSLR and start off simply by adding Ha to DSLR images, and then work my way up to doing filters as I can afford them.  The idea of a motorised filter wheel bothers me as I feel it is not only expensive but just one more thing to have to learn to operate and one more thing to go wrong or have issues with USBs.  

Will ponder some more and do some research on the chips and prices.  

Does any-one have experience of the QHY8L camera and or the capture software it comes with?

Carole

[RobertM]

Does any-one have experience of the QHY8L camera and or the capture software it comes with?

No but I have the SX equivalent and have posted images with it.

Robert

[MarkS]

The thing is, choice of astro-camera is a real compromise.  Once you've got used the the chip size and pixel count of the DSLR you end up wanting the same thing in an astro-CCD and it simply doesn't exist at the present time (at least not at a sensible price).  Chris's recommendation is a really excellent Sony chip and I seriously considered myself but it is a lot smaller than the standard DSLR chip so I would be wasting quite a lot of field of view. The Kodak 8300 is a bit bigger than that Sony one but still smaller than a DSLR and it is less sensitive and is noisier (both in dark current and in read noise) than the Sony one - it needs a lot more cooling.

It's the main reason I haven't yet taken the plunge into the mono-CCD world.  The Bananascope is a very fast photon grabber ( F/2.8 ) so it overcomes the main disadvantages of a DSLR.  So I'm not in a great hurry to change.

If only Sony made a larger version of that chip - it would be a killer chip in the astro world.  But it wouldn't have any other mainstream uses so it wouldn't be commercially viable.  Kodak is technically bankrupt and their range of chips has already been reduced. This doesn't bode well for the future, either.

If only there were mono versions of some of those DSLR chips.  A cooled astro-camera made from one of the those would be worth having!

[Carole]

So if Kodak is technically bankrupt, how does that affect those who already own a CCD with a Kodak chip when it comes to guarantees etc?

Carole

[MarkS]

Dunno.

The CCD part of the business has already been sold off as Truesense Imaging in order to raise much needed cash for Kodak.  I read somewhere that Truesense has already discontinued some chips in the range - I think that's part of the reason the SBIG range of Kodak based cameras has shrunk:
http://www.sbig.com/Cameras_At_A_Glance.html

Mark