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Stiff Focus Ring on SMC-F 50mm f1.7

Gyotto
Posted 08/02/2014 - 20:52 Link
Hi all
I have a little problem...
Just got a really MINT copy of a Pentax-F 50mm f1.7
Cosmetically is perfect, the lenses are perfect, no CA at 1.7, rly a good copy.
Auto focus is precise and accurate too.
PROBLEM:
Te focus ring is a bit stiff, especially near infinite. I can hear that the servo motor slows near infinite.
I have another copy of this lens, the focus ring is rly fluid and the servo motor runs faster and without to slow in any point.

I removed the filter ring support, cleaned the old grease (that was dirty, gray) and replaced with a liiittttttllleee bit of LITHIUM grease on the elicoid, but the stiffness do not change at all.

Any advices?

Thanxxxxxxxx

P.S. sry for my english.....
Edited by Gyotto: 08/02/2014 - 20:57
dpm
Posted 08/02/2014 - 22:30 Link
You're likely on the right track. Clean carefully, again, and grease again. Look especially for a spec of debris embedded *in* the root of the thread.

If nothing is obvious, try assembling dry then working the screw, then lok for a shiny area or material being shed.
python118
Posted 09/02/2014 - 15:42 Link
Hi, sounds like it may have been dropped, causing a bit of distortion

Regards Dave

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