Astrophotography with CCD cameras
I am presently working with two black&white surveillance cameras that can add multiple frames internally. That results in exposure times from 1/10000 seconds up to 2.5 seconds in case of the Mintron MTV 12V1C-EX (left) and from 1/25 seconds up to 10 seconds for the Watec WAT 120-N (right). Both cameras are equipped with high-sensitive low-noise SONY CCD-sensors but not cooled. Even in summer nights at moderate temperatures the number of hot pixels is very low. Especially the Watec camera can be compared to native CCD-cameras for astrophotography. It just lacks cooling and exposures longer than 10 seconds. On the other hand, this is even an advantage because with maximum 10 seconds exposure the polar alignment and guiding accuracy are far less critical. The tracking accuracy of my mount is sufficient and a rough polar alignment is enough to get decent images made by stacking of several hundered frames of 10 seconds each. Also, as mentioned elsewhere on my website the seeing, wind gusts, satellites, aircrafts, clouds and many other nuisances are less critical with such comparatively short exposures. I always have the possibility to define a personal critical quality level for each series of frames and an I am free to discard all frames that are below that level. Usually the rate of discarded frames is low but can be as high as 50% if the conditions are poor.
| Mintron 12V1C-EX CCTV camera Sensitivity comparison of Watec WAT-120N and Mintron 12V1C-EX CCTV-Camera attached to the telescope Comparison of different frame grabbers OES CMOSfB camera |