CCD : CMOS ?

[Capricorn]

Looking at a simple imaging camera and I keep noticing that manufacturers say CMOS for planetary and CCD for Deep Sky.

Why ?

Is there a reason why CMOS cannot, or should not, be used for Deep Sky ?

[RikM]

Basically, you can use either type for either target but a CCD camera will generally outperform (and be more expensive than) a CMOS camera.

CCD is generally more sensitive and with lower thermal noise, so better suited to faint targets. CMOS sensors are okay for brighter targets like planetary images, but even the better planetary cameras use CCD sensors.

[riklaunim]

Looking at a simple imaging camera and I keep noticing that manufacturers say CMOS for planetary and CCD for Deep Sky.

For years CCD technology was ahead of CMOS. Right now due to mass usage there is a lot of development going in the CMOS range of sensors, but still there is nearly no CMOS sensors good for DS imaging (big in size, with relatively big pixels, low noise). Aside of DSLR mass market doesn't need big sensors so most modern CMOS are very small with very small pixels.

There are some option, but also as you noticed "CMOS" has a bad reputation in amateur astronomy so even if a CMOS based camera would be created with good specs - it would have some problems proving thats its actually good

For example CMV4000 - http://www.cmosis.com/products/standard_products/cmv4000 - bit smaller than KAI-4022 in Atik 4000. For a CMV4000 machine vision camera (USB3/GigE) capable of up to 90 FPS at 2048 x 2048 you would pay 1500 - 1800 EUR. When put to much slower DS-optimized electronics the price should be lower. Atik 4000 would be 3,5 times more expensive, but would the CMV camera would be 3,5 times worse than KAI ? Nobody checked that I think

There is also e2v EV76C660. It has the same diagonal as ICX274 found in Atik 320E. It has similar low read noise (3-4e), unknown low dark current... and insane ~80% QE max. Also not tested in DS-type camera.