784141.fig.001
Figure 1: Limiting magnitudes for various configurations of objective diameter and CCD used. The Sony ICX285AL 1388 1036 CCD with 6.5  m pixels and read-out noise, without and with the image intensifier used to effectively shorten the focal length 7.7 times, is compared to the Andor 1024 1024 EM-CCD with 13  m pixel and read-out noise. The objectives are assumed to have 1/1.2. Vertical gray lines mark the objective sizes of FAVOR and TORTORA cameras. Numbers inside the lines represent the corresponding sizes of the field of view. The limiting magnitudes are in band for 0.13 s exposure. For TORTORA camera, the effective diameter is shown, which is times smaller than the input window size due to multi-mirror objective design which reflects back approximately 50% of incoming light. The variant with a low-noise EM-CCD is obviously the best in sensitivity, while the one with the image intensifier is far superior in a size of field of view.