On 1/29/2023 4:02 AM, Ciprian Craciun wrote:
Hello all!
I'm a long time lurker, but in the last few years I've not focused
seriously on photography, thus if what I'm asking about might have
already been discussed please point me in the right direction.
So, I have the following problem with a Pentax D-FA 100mm macro lens:
the aperture system on the lens is sluggish to respond and thus all
images are overexposed, especially on high f-stop numbers (i.e. 5.6,
8, 11 and onward).
Has anyone encountered this problem? How has one solved it? I'm
especially interested in do-it-yourself approaches, as I doubt I can
send the lens to be serviced (without costing more than the lens
itself)...
Lazy aperture syndrome. It's almost always caused by a small amount of
whatever lubricant they use in the mechanism migrating onto the aperture
blades making them sticky.
I've never torn down a lens and put it back together with any success,
but if it's what I think it is, the lens needs to be disassembled, the
blades need to be removed and cleaned, then the lens needs to be
reassembled and recollimated.
bill
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