DSLR or CCD?

[Beardy Bob]

OK, following my thread on 'conditions or processing?' earlier today, now I'm on this one.

Do you think that results with a DSLR can ever match those taken with a dedicated large frame CCD or is the CCD technology just hugely superior?

OK, so you might have to modify the DSLR to get a comparable wavelength range response, take separate RGB to ensure a sharp focus with each wavelength and take more data to allow for the DSLR having increased noise and being a CMOS device with smaller pixels and hunking great transistors sitting next to each pixel, etc. BUT, in theory...

[blinky]

In theory NO...... and in practice NO, well not the same as a dedicated cooled CCD large format sensor - they are dedicated astro imaging kit. Remember though that a modded 350d/450d/1000d will come in around £500/600 which is a lot less than anything dedicated astro CCD related. As far as I am aware.....

[Beardy Bob]

Why not though?

[SteveL]

...because the CCDs are cooled and suffer less issues with heat related noise in long exposures.... but they are more expensive because of that

[Whippy]

Plus I would imagine economies of scale come into play too. Canon sell thousands upon thousands of DSLR's while Starlight Xpress sell a darn sight less of their large format cameras.

Tony..

[themos]

CCD cameras also tend to have a much larger dynamic range (that means less noise) and much better quantum efficiency (more sensitive to photons).

[Sparrow]

I don't think it's possible to beat the results of a large chip dedicated CCD camera with cooling etc, but I had to go down this decision route a few months ago and budget played a large part in my decision. For a CCD camera worth buying the cost is considerable whereas I got a Canon 1000D including 18-55mm lense, and a Astronomik LP clip filter for about £500. It's not modded so that I also have a good daytime camera. The results may not be as impressive as a dedicated CCD but they're not bad at all.

[narrowbandpaul]

CCD fabrication uses very specialised processes and equipment. All of which are optimised to produce good performance.

CMOS will have transistors in the pixel which take up space, reducing fill factor.

CCD's have lower read noise and higher full well than most DSLR's, and hence dynamic range is higher.

CCD's are cooled whereas DSLR's are not. Thus for most sensors dark current is not the limiting factor

because the CCD is a good detector it does cost more, also becuase of the special processes involved in fabrication

also the camera manufacturer (like Starlight Xpress, ATIK, SBIG, FLI etc) is important. Just because they use the same sensor doesnt mean you get the same performance.

The camera manufacturer is the one who introduces the amount of cooling, RBI inhibition, the circuit boards used to supply voltages and clock the CCD. Do it well and the camera is great. Do it wrong and the camera could be seriously underperforming.

a good QE, low read noise CCD camera from a good manufacturer will deliver the best images.

[blinky]

I know we are talking about economies of scale etc but the QHY8 is well over a grand but uses the same sensor as the Nikon D50 (I believe) you would think that the cost of the lens, CCD Preview screen, mechanics of the mirror in the D50 etc etc would outweigh the economies of scale issue as well as the cost of the cooling (We know how cheap a peltier element is to buy from Ebay!) but the QHY8 is still over twice the price of a D50!

[George]

Ive been a DSLR user for 2 years now and my choice was down to one thing....budget. There are some very skilled DSLR users about whose images when compared with the dedicated cooled CCD are hard to tell apart, processing the final image is the key too so being profiecent with photoshop etc plays a big part.

[callump]

<tuppenceworth>

DSLR's will be fine for pretty pictures - but will be limited if you want to do any science, like photometry, astrometry, etc. And if you want to do interesing imaging like narrow-band work, you would be better off with a dedicated b/w ccd camera and filters.

</tuppenceworth>

/callump

[narrowbandpaul]

even for pretty pictures, the CCD is the tool of choice.

for narrowband a monochrome CCD will be by far the better choice.

[Sam]

even for pretty pictures, the CCD is the tool of choice.

for narrowband a monochrome CCD will be by far the better choice.

except where you haven't got a big budget, then the DSLR becomes the tool of choice.

[Whippy]

I think we can sum this up quite easily. If you're on a budget or already have a DSLR, then it's a no-brainer, DSLR's offer wide fields at a low price but you do need to work a bit harder to obtain great images, especially where nebulae are concerned if the camera isn't modded.

Cooled CCD cameras offer greater sensitivity, no big issues with cooling and in the case of mono cameras, easy narrowband possibilities. All this comes at a cost which in the case of large format models, runs well into four or even five figures.

So, if you've got the money CCD cameras are the tool of choice but DSLR's are certainly capable of doing the job too.

Tony..

[Takahashi]

Yep, it's a simple cost issue for me. I'd dearly love to get involved in narrowband imaging, but it is quite simply not going to happen. Several thousand quid for a CCD imager, and potentially thousands more per filter, puts it firmly in the "Never gonna happen" bracket for me. Having already shelled-out thousands for the basics; scope, mount, laptop, accessories... I've hit my limit for many a year.

/checks last night's lottery ticket...

[adamsp123]

Has anyone used a modded DSLR for narrowband imaging? If affirmative did it work OK?

Pete

[Whippy]

Yep, it's a simple cost issue for me. I'd dearly love to get involved in narrowband imaging, but it is quite simply not going to happen. Several thousand quid for a CCD imager, and potentially thousands more per filter, puts it firmly in the "Never gonna happen" bracket for me. Having already shelled-out thousands for the basics; scope, mount, laptop, accessories... I've hit my limit for many a year.

/checks last night's lottery ticket...

Thousands?

Atik 16hr camreas are occasionally seen secondhand and they normally go for between £600 - £800 and a Ha filter costs £125 (Baader 1.25" 7Nm model). So for less than a grand you can have yourself a really sensitive narrowband kit.

Tony..

[Takahashi]

Seriously? Less than a grand?

Uh-oh... credit-card is a-tremblin' all of a sudden.

TBH, most of the dejection in my previous post was based on the prices of some solar narrowband filters such as these : Hydrogen-Alpha (Ha) Filters for Observing the Sun - OPT Telescopes

[skye at night]

I have seen it done with a modified one...

Not too bad, but as said above .. not ideal if you are doing the real scientific stuff..

But then.. how many of us do that...

I would love a cooled ccd camera and I am trying to source a decent second hand one...

I really couldn't justify buying something at 3000 pounds however just to find it coming out on very infrequent occasions...

2000 is a good limit for a first ccd whether new or second hand..

A good dslr as also note above is also a good all-round camera.

Plus for me.. i have some very good canon lenses to make use of, but I would love to see what a good ccd could do with them also.

Steve

[Whippy]

Seriously? Less than a grand?

Uh-oh... credit-card is a-tremblin' all of a sudden.

TBH, most of the dejection in my previous post was based on the prices of some solar narrowband filters such as these : Hydrogen-Alpha (Ha) Filters for Observing the Sun - OPT Telescopes

Ah, the solar kit (with the exception of the PST) is a completely different ball game and as you've noticed, hugely more expensive! Night time narrowband filters are mostly much more affordable.

Tony..

[Takahashi]

That's good news, as I'd like to eventually get into narrowband nebula photography, once I'm up-to-speed with guided work in general.

[ollypenrice]

I'm quite surprized by the concensus, budget apart, in favour of CCD. Surprized, yet I wholeheartedly agree with it. I think that on some objects a DSLR can come close. I like a lot of DSLR nebulae which do look nicely nebulous, as they should. But I have never seen a galaxy image up there with the best from a CCD. (That doesn't mean they don't exist.)

You should indeed pick up an SXVH9 or Atik 16HR/314L for less than a grand. The other issue is, how nice are they to use. Personally I find DSLRs a nightmare in the dark, but that's just me. The whole process with a CCD is logical, physically comfortable, and you are using it as intended.

Just a word about 'pretty pictures.' I have never met an imager who tried to take 'pretty pictures' but I have met plenty who say that that's 'all they are trying to do.'

Of course there's a valid distinction between that and scientific imaging but - and this is a big 'but' - every astrophotographer I know is trying to take BEAUTIFUL pictures. That includes me. There is a very big difference.

Olly