Oh dear, front of my lens wobbling!

ChrisR

ChrisR

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Took my Pentax ME out this morning (and the Canonet QL17 loaded with Vista) and when I got it out of the bag, the front of the Pentax-M SMC 50mm 1.7 lens was loose! It wobbles about a mm or so, side to side. I'm not sure whether to

a) ditch it and get a new one (which opens up the possibility of choosing a different prime that might work with other cameras, if and when...),

b) send it off for a repair, or

c) have a go at repairing it myself!

I should say, I'm not very DIY-oriented, and do have some grip and dexterity problems in my right hand. But I did find this in a lens review by "stoogie" on Pentaxforums, re a different lens (50mm SMC-M 1.4): "I picked this lens up on craigslist for a great deal, as it needed some repairs. The front barrel was loose, and the glass actually wobbled around too. I'd heard that these old lenses were really simple, and I trusted my DIY skills enough to pull off the name plate and have a look. I tightened up one screw, and now I've got a perfectly functioning lens"

From PentaxForums.com: http://www.pentaxforums.com/lensreviews/SMC-Pentax-M-50mm-F1.4-Lens.html#ixzz2AmLS06He

Any opinions?
 
Which bit in particular is wobbling? I've seen a Pentax SMC 55mm f/2 "wobble" and it turned out to be almost entirely the trim/cosmetic rather than any actual glass.

They are pretty logical and simple lenses from a construction point of view.

1mm is a tiny amount though...
 
The whole lens rattles if I shake it! The front element moves in and out by about a mm or so. If I hold the front element out on one edge, the other side will still move back and forth (not the same behaviour the other edge).

Looking at it, I've no idea how you'd get the front off. There are 5 minute philips style screws on the back plate, but nothing on the front, except that right against the glass there are two tiny notches at 180 degrees. So how you would "pull of the name plate", I don't know!
 
wickerman said:
There is more information on the problem and fix's here : http://www.pentaxforums.com/forums/...shooting/172443-how-fix-loose-front-lens.html

Hope this helps.
Click to expand...

Ah yes. Closer inspection shows the glass element is not in fact moving, so it IS the filter ring. I'll have to give this a go... Now to try and find a ring or tube of the appropriate size to press against the name plate... a toilet roll tube is the right size, but won't grip and turn, hmmm...

In the end, none of the recommended approaches seemed to work, except a finger nail in the T of PENTAX, turning the name plate very slowly until loose, then a roll of blue tack as a winder, and off it came. 3 tiny little screws had obviously come undone. Mini screwdriver set from a Christmas Cracker of a few years ago, and they are nice and tight again, all reset and cleaned up. Job done!

Thanks everyone!
 
Just had to do this again, after only 2 months. I think maybe the cheapo christmas cracker mini screwdrivers are not up to tightening the tiny screws properly. I did put some on my Xmas list but no joy so I guess I'd better buy some!
 
Try putting a small blob of clear nail varnish on the screw heads once tight, this should stop them from loosening.
 
Purple or blue Loctite on the threads. Breaking the bond is a bit more difficult on very small screws if you use blue, because you can't apply much force, if you ever want to loosen them again.
 
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