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08-05-2010, 11:31 AM   #1
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Question on my first M series lens

Hello all! I just bought, for a very reasonable price, a M 55mm f1.7 lens. The lens looks in near perfect condition for it's age, with the exception of a couple specs of dust on the internal elements. My question is, that on the external lens around the very edge, there appears to be a fine coating of something on the lens, that you can see when you tip and tilt the lens in direct light. Maybe left over finger grease from years of cleaning? Maybe something left over from the manufacturing process? As this is my first vintage lens, I have nothing to compare it to. What are your thoughts?

Please don't say fungus

Thanks in advance. You can see a little of this just to the left of the light reflection on the top of the lens.

Last edited by void7910; 08-05-2010 at 11:38 AM.
08-05-2010, 11:42 AM   #2
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That's definitely not fungus- it looks more like cleaning marks/smudges.

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08-05-2010, 12:03 PM   #3
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Wrap a piece of lens tissue around the end of a toothpick and dampen it with some cleaning solution. That will likely take care of what you are seeing.

Congrats on one of the best fast 50s out there and welcome to the forums!

08-05-2010, 03:56 PM   #4
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Or a lens pen will do the job and if you don't have one I think even a microfiber cloth and your breath will work.

08-05-2010, 03:59 PM   #5
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I had an A series lens with the same issue. A clean with a lens pen shifted it in no time.

Anyway congratulations on owning a Pentax classic. The M 50mm 1.7 was sold as part of the "kit" when I bought my MX new in about 1980. I still have it and I still use it today. Like all the K and M series lenses it screams quality, and produces quality. Getting the exposure right takes a bit more effort as the "green button" method is not perfect, but use the histogram to guide you and you be delighted with the results.

One bit of advice is must get a hood for it. A metal one that has a 49mm thread will do the trick. The old glass does not have anti-flare coatings as good as modern glass. Also the digital sensor is more sensitive to stray light than film is. So if you shoot in sunlight without a hood you may get flat (lacking contrast) results. Pop on a hood and you are good to go.
08-06-2010, 04:13 AM   #6
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thanks all! I had a go at my new purchase with a lens pen last night and she came up beautiful as ever!

thanks again

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