| | Despite the fact that the G2 and G3 cameras share the same
adapter mounting interface, Off-Axis guiders
for G2 cameras with either M42 or M48 variant of mounting thread
cannot be used with G3 cameras. The mirror reflecting light to guiding
camera inside the G2 OAG is positioned too
close to the optical axis that it partially shadows larger CCD detectors
of G3 cameras. And G4 cameras use even greater detectors and their
adapter mounting interface is also larger. Off-Axis guiders for G3 and
G4 cameras have to be designed from the ground up to place the mirror
feeding the guiding camera with light as close to the optical axis as
possible on the one side, but not to cause vignetting (shield the main
CCD detector) on the other side. |