Forum: Pentax SLR Lens Discussion
03-15-2015, 12:18 PM
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When the lens is vertically up or down the clamp, when on, increases the resistance on the focusing ring to prevent focus creeping away from the set position.
It works that way on my copy of the SMC Pentax-FA Macro 100mm f2.8 lens. The big brother of the 50mm.
Regards
Chris
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