Infinity on P5017

[pickle]

I have a Planar 50/1.7 MM, which used to focus fine at infinity (sharpest star images I've seen at that aperture), but no longer does. I noticed during recent low-light shooting that at infinity, anything wider than f/4 shows out of focus. I have read the post below, about the 85/2.8, and just want to check that Wilson's advice holds true for this lens, before I start cutting off the rubber. If so, what is the best way to remove it, and can it be done sufficiently carefully that the rubber can be reused, or does it need a new one? Any help much appreciated - this problem is spoiling a super lens.
Thanks,
Mark

 

[wilsonlaidlaw]

Mark,
You don't need to cut the rubber sleeve and should be able to get it off with little trouble and even if it stretches a bit, it will usually shrink back over a week or so. A thin bluntish edged letter opener is a good tool to ease it off. You can use Pritt stick to glue it back on non-irreversibly. Word of warning - the screws can be very tight, I suspect they may use a thread locking compound at the factory. Make sure the lens is held firmly and use a high quality, correctly sized jeweller's screwdriver with tommy bar if needed. Best of luck - Wilson