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09-15-2010, 08:44 PM   #1
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Odd loss of paint inside a Pentax-A 50mm...

So I recently bought a used Pentax-A 50mm f/1.4 from a camera reseller who rated it EX+, and while cosmetically it is very good (see the exterior shot to see what I mean), and mechanically focusing is good (it's not totally smooth, showing a bit more resistance in two locations during rotation), and the glass looks perfect, there are a couple of things I was wondering about.

First, on one of the aperture blades there's a small dark spot which stays there, and I've opened and closed the blades a few times and it doesn't move (see my 100% crop). I'm not sure what it is, and was wondering if anyone had any ideas.

Second, one the interior of one side of the lens it looks like paint has flaked off or something... there appear to be exposed silvery bits, and while you can't see it at all looking straight on (not surprising though considering the way the glass bends the light), it is visible at an angle from the side, and I've captured it as best I can in my last shot. I can't say I've ever seen anything like this in lenses before, and I was wondering if anyone had any idea what it was. I'm assuming it's some sort of paint loss?

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09-15-2010, 11:15 PM   #2
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It's difficult to determine w/o looking at the actual lens, but I am quite certain the lens was repaired b4, unprofessionally. The unsmooth focus ring is the 1st sign. The black dot on the aperture blade looks like concave/dent and being repainted. The 2nd or 3rd element from the front was probably cleaned and the black paint on the glass rim was somehow removed. This might induce flare.
09-16-2010, 05:06 AM   #3
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To me the black flake looks like a part of the paint that detached somehow.

The irregular focus ring cannot be linked with certainty with bad repairs. It could very well have been knocked or dropped at some time. That happened with the 2nd hand DA21 I bought, the focus ring had resistance in one area. Realigning the tumblers inside the lens (done by a professionnal) fixed things.

I would suggest you send those pics to Eric, he might be able to diagnose the issue.
09-16-2010, 03:14 PM   #4
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Thanks for the suggestions... I emailed Eric, and he got right back to me, but for the cost of the repairs, I might as well return the lens for a refund since I just got it.

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