I must be missing something .. This is the first time I've heard of a "CB" lens... could be, but ... Are you sure of that model?Originally Posted by brent8927
Anyway... In the "C .." lenses - with between-the-lens shutters, the shutter *must* first close before anything else happens; if it did not, light would reach the film during some of the necessary activity - diaphragm closing, mirror swinging out of the way, rear film plane "vanes" in the process of swinging out of the way.
This initial shutter closing, is in all my "CF" lenses, *very rapid* ... faster than the eye can perceive the motion.
To see what happens, in the 500 series 'Blads, directly under the boss on the right side, where the winding knob is mounted, there is a "mirror release" latch. If this latch is "lifted" with a cocked shutter, the shutter will close, the mirror will retract and the rear vanes open, but the shutter will not reopen for the exposure (a feature to be used to eliminate mirror, etc., shock in critical exposures). Try it with the lens mounted and the back removed. It should happen*VERY* quickly .. If it does not, the shutter is sluggish,and probably in need of cleaning, and timing.
After using this mirror release, the shutter release button must be pressed to activate the shutter, and complete the exposure, before anything else can happen.