No Subject

["Bob Howard" <bobh@xxxxxxxxxxxxxxxxxx>]

RE: Larry Haines wonders about the mirror (Matsukov et al) tele lens 
500mm. They are typically f/8 in the 500mm, (a Zeiss F/5.6 one cost 
an arm and a leg>) They do not stop down..so f/22 isn't a 
possibility. (I do have one with discs that sort of adjusts 
exposure). Also the f/8 is a physical f/stop and the secondary mirror 
cuts out part of the light so it is effectively f/11. Depth of field 
in very shallow so not for stereo execpt at infinity where one would 
have to use hyper to get anything. They do not hand hold well either, 
except some of the latest cameras might let you use 1/2000-1/8000 if 
you had fast enough film to use f/11 in sunlight. BobH


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