Can you say me if the CCD SBIG ST2000XM is a good camera for photometry ?
ABG camera and CCD KAI ?
You didn't mention which scope you might be using. Usually, you might want to first consider the pixel scale for the scope you plan to use. There are some calculators on line such as at:
The camera has 7.4um pixels so it would be more suited to scopes with shorter focal lengths. Also be sure about the camera model number the 2000XCM is a one shot color camera.
ABG cameras are probably not the first choice for photometry though they can be use effectively if you are careful to keep exposures in the linear range. The ABG is provided for imaging so that as pixel wells fill they overflow electrons to a drain instead of saturating the nearby pixels. That is handy for pretty picture imaging but you don't want to loose those electrons for photometry. The drains also take up part of the pixel area so the detector has smaller wells to hold electrons.
What do you think about the CCD monochrome ?
A friend of mine is using one and he likes it very much. The images are very uniform and his photometry has been very good. He is being careful with exposure times. He makes trial exposures on a field and measures various comps before he settles on the exposure he'll use. It's worked fine. He has had trouble keeping moisture out of the camera, it is an ST-2000.