Mark on front element...problem?

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I am looking at a used lens for sale, and noticed a very slight frosty-looking mark of short length, and narrow width, along the periphery of the inside of the front element. It's so narrow as to be not very noticeable until looking through the lens from the rear element. I am wondering if this would show up on an image? Even wide open? I don't think it would, but I do not know for sure. I guess this question is somewhat technical, since is the entire exposed front element used for the image that hits the film? Thanks for the answers...

-- Fred (yuma@yahoo.com), March 20, 2002

Answers

I should add that the mark is on the inside of the element, so it's not a cleanable mark.

-- Fred (yuma@yahoo.com), March 20, 2002.

Fred: Most likely the "mark" will not affect the image on film. It may be a spot of fungus or some "imperfection" on the inside surface of the lens.These things almost never affect your image.If you ever did want to have it cleaned or removed, the lens would have to be taken apart, and that costs money. Best of luck with your decision.

-- John Alfred Tropiano (jat18@psu.edu), March 20, 2002.

It looks shiny, like a mar. I wouldn't want to have it disassembled, etc. Owner says it's never been disassembled.

-- Fred (yuma@yahoo.com), March 20, 2002.

What lens is it?

-- Andrew Schank (aschank@flash.net), March 20, 2002.

Fred: If you do not want to have the lens taken apart and the "mark" removed, I would just purchase it as it is since the "mark" will most likely not affect your image.Sometimes, flakes of material from the inside of the lens come loose and stick to the lens surface. It might be a spot of paint. No matter since it is so small.Does it move around at all when you change the position of the lens or does it remain in one place? Good luck.

-- John Alfred Tropiano (jat18@psu.edu), March 20, 2002.


The mark stays put. I was thinking (and in answer to the above question), that since it's a longer length lens (75), that the extreme periphery would not show on the image. Perhaps when assembled the mark was left? I'll just try it out, thanks for the answers.

-- Fred (yuma@yahoo.com), March 20, 2002.

I have seen long thin (wispy) faint lines on inside elements of some older lenses. They look like marks that come from cleaning of soft coatings, except that they are on internal lens surfaces. I don't really know what they are, though. They are not fungus, as this ususally looks circular and floral in appearance. It could be the lens was disassembled and cleaned (inexpertly) at some point, although I have no way of knowing. The only thing I can say is that this sort of thing is puzzling, and it doesn't look anything like the usual suspects (fog/haze, fungus, or separation).

-- Eliot (erosen@lij.edu), March 20, 2002.

As the lens has a mark, you should be able to get a large discount off the average market price?

-- Karl Yik (karl.yik@dk.com), March 21, 2002.

Upon further inpection, the mark is along the bottom of the front element when looking at the lens on the camera. So, since we have a 35mm frame that's more long than tall, this would probably preclude the mark ever having a chance of showing on the film.

-- Fred (yuma@yahoo.com), March 21, 2002.

Fred:

If it's right at the periphery, it may be a small amount of separation where the glass meets the metal - I have a 28 with a mark that matches your description, and that's what mine is. It's just a small bit of air that's gotten in between the glass and metal, and lens guru John van Stelten told me not to worry about it - it's not likely to spread, and since it's in a part of the glass that's set against opaque metal, it's not in the image path anyway.

My mark is silvery, follows the circular edge of the glass for about 10 degrees in length, and is a mm or less in width.

-- Andy Piper (apidens@denver.infi.net), March 21, 2002.



Thanks for the info Mr. Piper. My mark matches yours. I am wondering if instead it is a scrape from mounting the element perhaps? Maybe it is what you described it to be. But, it is visible not against any metal, ie: it is a tiny hair away from the lens barrel into my line of sight, but I can see what you're talking about with yours. Anyway, minutia, that will not show on film. Thanks for the input.

-- Fred (yuma@yahoo.com), March 21, 2002.

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