DSLR and CCD chips

[Lee]

I'm curious to the real differences between the common DSLR chips (ie 350D /D70 etc) and smaller CCD - say DSI Pro.

They seem to have similar pixel sizes - all ballpark 7-8um....
DSLRs have much larger chip.

So - Both should capture a similar resolution image with any given telescope - right?
But the DSLR will capture a larger FOV.
The DSI pro (or other monochrome) - more sensitive due to no Bayer matrix - right?
CCD needs no mods for Ha imaging.
What about noise levels - I thought CCD had less??

Is this it in a nutshell?

[bojan]

yes......
CCD is much less noisy, compared with CMOS.

[Striker (Tony)]

Lee your pretty much on the right ball park.

CCD's are more sensative...and a lot more work.

When it comes to colour ccd's I don think there worth the money...must be monochrome otherwise just get a dslr.

[jase (Jason)]

Tony has hit it right on the head. Sensitivity is a major characteristic. However there is more than just CMOS vs. CCD. One should also look at pixel well depths and interline vs full frame. If you look at SBIG's site you will notice they have a combination of interline and full frame cameras. Full frame delivers better results, but it hasn't stopped many still using interline (found in the STL11K)
You may wish to check out Kodak's site for more info:
http://www.kodak.com/US/en/dpq/site/...esRoot_product

While your there, check out this monster;
http://www.kodak.com/US/en/dpq/site/...-39000_product
39Megapixel full frame download CCD chip with a 6.8µm pixel size. You'd cover an incredible amount of sky with one of these attached to an astrograph. Crazy stuff.

[avandonk]

That was the quandry I was in. So I settled for the Canon 5DH. It has 100,000 e well and 14.3 stops of dynamic range and full frame. The pixels are 8.4x8.4 micron. For a colour sensor it is as good as it gets. The only thing better is a full frame Sbig or equivalent. Or a peltier cooled 5DH!
The other consideration was dedicated CCD's dont work with Canon all electronic lenses such as the 300mm F2.8L.
There is no 'correct' or 'best' sensor, it depends what optic you match it with and how much you are willing to part with.

Bert

[74tuc]

Hello Lee,

About " ... What about noise levels ... " what really matters is "signal to noise ratio" cooling (to reduce thermal noise and lower dark currents), choosing low noise amps, designing the CCD's to produce low readout noise etc. On the processing side one does dark frame subtraction, stacking images etc.

In my case I am interested in locating dim objects - comets and asteroids - so I use a sensitive low noise camera (MX916) that uses a Sony ICX083 CCD. The pixel size is 11.6 x 11.2 micro-metres (I use it in the binned mode giving 22 X 22 micron pixels) full well capicity is 300,000 e- and the readout noise of about 15e-. Dark current accumulation is 0.1 3e- per second.

For short exposures (5 min to 8 min max) dark frame and flat field processing is not required.

Rgds,

Jerry.