75/4.5 Nikkor-SW and front element (center) mark from filter/front cap?

Hi -

I am looking at a 75/4.5 Nikkor in a Copal 0, and it has a small hazy mark (1-2mm dia) dead center on the front element.

The plastic Nikon front lens cap has a small pip in the center of its back ("inside"). I have surmised that the mark was caused either by (1) screwing down a filter (presumably with the wrong type of mount) on the front element or (2) the plastic pip contacting the glass. The spot has not responded to a lens pen nor ethanol or methanol, which makes me doubt it is plastic rubbed into the front coating. Maybe at best the coating of the filter rubbed off onto the lens element.

Are these marks common on this lens? I have not encountered this save on one SLR lens that had the "wrong" filter mounted (actually, it was a filter with loose glass). That mark actually came off (how, I'm not sure; a repairperson did it - and it did not kill the front coating on the lens - which makes me think it was rubbed off coating from a filter).

Thanks!

I just checked mine, which is in prestine condition. The front glass is situated deep enough to clear the filters i use, even screwed in the whole way. But i can imagine a soft lens cap being pushed onto the lens when packed too compact. When handled rough, for instance when trecking, this could some damage to the coating.

There are more lenses where te front element is very close to the filter, for example the 110mm super symmar, is one. Handle them with care or make some kind of spacer. A cheap filter of the right size without the glass will do trick nicely.

Also beware of using generic lens caps. Modern lens caps often do not clear older lenses.

Thanks guys!

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Originally Posted by Huub

There are more lenses where the front element is very close to the filter, for example the 110mm super symmar, is one. Handle them with care or make some kind of spacer. A cheap filter of the right size without the glass will do trick nicely.

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Thanks for pointing this detail out about the 110mm SSXL, as I have one I bought from a friend a year ago that I decided to put a step-up ring on because it had some minor damage to the threads on the outer barrel of the front element. I then had to change the front lens cap to fit the stepped-up diameter. I think the step-up ring serves as the added spacer you describe, and so my new lens cap will not marr the glass. That 110SSXL is a sweet lens, and I probably lucked out that I haven’t marred the front glass.

Quote:

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Hi -

I am looking at a 75/4.5 Nikkor in a Copal 0, and it has a small hazy mark (1-2mm dia) dead center on the front element.

The plastic Nikon front lens cap has a small pip in the center of its back ("inside").

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I had the same problems many years ago with a Rodenstock 55mm Grandagon. Which also the front cap with a pip in the center damaged my coatings in the middle of the front element! I spoke with Rodenstock and they told me send the lens to us! They handled it and the damage was gone, at no cost for me, and the lens was at least 6 years old. After this I checked all my lens caps and found many more with a pip in the center and I did all remove with sandpaper!

Have gone to a very reputable eyeglass store in the past, and they were able to 95% get rid of a terrible scratch on the front of one of my lenses. For relatively little money, they saved my lens.