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Old 16-06-2009, 11:46 AM
TrevorW
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What benefit if any CCD

Ok I've been tossing up entering the field of CCD cameras but my budget can't stretch beyond $1500

Question is what benefit if any would I get from cooled CCD over my Canon 350d

The camera's I've been looking at ATIK, QHY6, have similar pixel size to the DSLR but smaller image sizes and do I go for a mono or colour bearing in mind mono incurs additional costs for filters.

Feedback

Thanks
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Old 16-06-2009, 12:32 PM
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... do I go for a mono or colour bearing in mind mono incurs additional costs for filters.
... and processing skills/knowledge.
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Old 16-06-2009, 12:45 PM
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What do you want to do with yuor camera- just pretty pics or some science. This changed the answer.
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Old 16-06-2009, 07:26 PM
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Mainly pretty pics I don't have time at the moment to devote to the science aspect
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Old 16-06-2009, 07:39 PM
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CCD advantages?, QE, low noise, well depth and dynamic range. Especially QE.
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Old 16-06-2009, 07:54 PM
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Fred what is QE, well depth and dynamic range say in comparison to a DSLR are you referring to a mono or single shot CCD

thanks
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Old 16-06-2009, 08:28 PM
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Well, QE on a DSLR is typically 15%, a CCD at least 35% (for a big chip) and over 50% (up to 80% peak) for a smaller one. well depth for a 40D is 25K (I think), a CCD is often 100K, noise is always much lower in a cooled CCD. Dynamic range on a 350D is 12 bit (14bit on a 40D), astro CCDs are 16 bit.

A single shot colour CCD is better than a DSLR, given the cooling and 16bit A/D convertor.
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Old 17-06-2009, 08:28 AM
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Well, QE on a DSLR is typically 15%, a CCD at least 35% (for a big chip) and over 50% (up to 80% peak) for a smaller one. well depth for a 40D is 25K (I think), a CCD is often 100K, noise is always much lower in a cooled CCD. Dynamic range on a 350D is 12 bit (14bit on a 40D), astro CCDs are 16 bit.

A single shot colour CCD is better than a DSLR, given the cooling and 16bit A/D convertor.
DSLRs do better than this. Typically 40% in the green. See the attachment from the sbig site. Their weaknesses are no cooling, nosier, 12 or 14 bit and low QE in the H alpha region
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Old 17-06-2009, 06:59 PM
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DSLRs do better than this. Typically 40% in the green. See the attachment from the sbig site. Their weaknesses are no cooling, nosier, 12 or 14 bit and low QE in the H alpha region

Well, it doesnt say if its a CCD or CMOS sensor. The CCD versions tend to be better in QE, but suffer from internal camera noise.
The CMOS sensors suffer from lower QE, but have better internal camera noise.
So you need to take those values with a grain of salt.
Realisticly, below 40 % as stated, but then remove your debayer film loss and that figure starts to hover around the 25 % QE.
This of course is the same for any sensor that has a debayer (Or similar) color incoding incorporated in the sensor, so remove around 15 to 20 % QE.
However, i believe that some of the FUJI DSLR cameras have proper pixels without any film/filters. To boot, i remember one model that can image from UV to deep IR. I tried so may times to get my hands on one, but to no avail. I read they were mainly manufactured to law enforcement for use in forensic applications (Special lighting for chemicals etc..)

Theo
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Old 17-06-2009, 07:56 PM
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....
Their weaknesses are no cooling,nosier, 12 or 14 bit and low QE in the H alpha region
Too right, especialy those paparazzi ones.
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Old 17-06-2009, 08:26 PM
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Gents this is all well and good but will a low end CCD/CMOS camera within my budget produce better images than a modified 350D
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Old 17-06-2009, 08:37 PM
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Are there any image comparisons that can be used to point out the merits of one or the other? Could someone show the differences between a CCD and a DSLR?

thanks

Frank
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Old 17-06-2009, 09:13 PM
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There are certainly the odd purlers out there but I have seen comparitively few "really" good deep sky DSLR images. The final imaging results from a mono CCD with colour filters in the right hands, while more time consuming to capture and process, will out perform a DSLR in similar hands in colour fidelity, resolution and noise everytime.

The problem is your price range, unfortunately there aint much in there I am afraid, you would need to go small chip or cheap one shot, but one shot will have a bayer matrix again so while your noise is lower due to good cooling compared to a DSLR down goes your resolution again

In my opinion I would spend the money on getting the best mount you can that will provide the best tracking possible then continue with your 350D DSLR and take long exposures ie several hours and use good darks and flats and you should be in business

Mike
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Old 17-06-2009, 09:48 PM
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The problem is your price range, unfortunately there aint much in there I am afraid, ..........

In my opinion I would spend the money on getting the best mount you can that will provide the best tracking possible then continue with your 350D DSLR...........
Mike
Mike's advice is on the money.

CCD's are without doubt still the gold standard, but are quickly becoming rare birds due their limited vertical market plus they are not mass produced and cost many $$$ as a result.

Sorry, if you want to make an golden omlet, you just gotta break some golden eggs!

FYI DSLR sensors have a well depths that make a mockery of "14 bit D/A's". All they are doing is resolving noise in smaller steps with this marketing BS.

The hallmark of a DSLR shot IMHO is the "all white" stars, due their (unless used with some skill) limited dynamic range.

CCD are optimisted for shots in the dark. DSLR's pretty much the opposite.
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Old 18-06-2009, 12:14 AM
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Gents this is all well and good but will a low end CCD/CMOS camera within my budget produce better images than a modified 350D
Trevor, I took the next step, sold my 40D, and moved to a qhy8. I also bought a 2nd hand starlight express mono camera to have a play with filters. The little starlight is more suited to shorter focal lenghts and now I have my tak adapters in hand I hope to get something out of it. Stay tuned
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