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Old August 9th 07, 09:15 PM posted to rec.photo.equipment.35mm
William Graham
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Posts: 4,361
Default Pentax 50mm A lens


"Mark Roberts" wrote in message
...
D.M. Procida wrote:

Paul Mitchum wrote:

Just got one of these from someone on eBay. Is it correct that to move
the aperture ring beyond f11 requires depression of the button on the
ring? On my 28mm ring the button is only required for the A position.

The button lets you use the A setting. If the aperture ring won't go
past f/11, then it might be time for repair.


It's pretty clear that the lock on the aperture ring mechanism is
faulty, and gets stuck just before f11. It can be moved past this by
holding down the lock button (though I can hear a metallic click as it
goes past).


I'm coming into this thread late so I may have missed the specific
A-series 50mm lens being discussed... but I'd guess it's the 50mm
f/1.7 - its aperture ring was made with inferior (probably cheaper)
material than that on the 50/1.4. If your lens is the SMC-A 50/1.7
then this is the likely cause; the indents in the inner side of the
aperture ring just get ground down. Sometimes this can be cured by
removing the aperture ring and giving everything a thorough cleaning
and lubrication. Sometimes this helps enough to make the lens usable.
You *might* be able to do it yourself, but it's easy to lose parts
(especially the ball bearing that clicks into the detents) when
disassembling and really tricky getting everything back together.

If you do lose the ball, this place has a huge variety of them...
http://www.vxb.com/ballbearings.html...FSA4hgods24arQ