[Dewman]

I have a Pentax-A 70-210mm lens that has a problem. Take a look at the photo 2nd photo, TL, and see if you can determine what this is. Is it delamination or separation of the lens elements?


It doesn't seem to have any adverse effects on the IQ of photos taken with it, but I've never seen anything like this before.


https://www.pentaxforums.com/forums/24-photographic-equipment-sale/300946-sal...10mm-lens.html

[tvdtvdtvd]

Based on the photo, I'd say it looks like a scratch. Does it appear to be on the outer surface of the lens or below the surface?

That far towards the edge, it shouldn't affect image quality. However, it is an unsightly blemish, so does reduce the value
of that very common lens.

[pepperberry farm]

that's quite a scratch... and seems to follow the curve of the barrel as well....

[Dewman]

The imperfection is on the inside, not the outer surface of the lens. Scratches? Possibly, but I doubt if it happened during the initial fabrication of the lens. An odd looking thing it is.

[Dewman]

If it's on the very outer edge of the lens, it could just be the blacking on the ground glass edge of a cemented doublet degrading.

Yes, DC.... it's only on the outer edge, and only on two areas, each about 1" long, almost directly across from each other. It's a shame, because I've found this particular lens to be quite good. I have another copy that is pristine, but I've compared images shot with both lenses of identical scenes and can't see any difference, despite the flaw in the one lens. Well built, but heavy enough to pound tent stakes with!

[LensBeginner]

Yes, DC.... it's only on the outer edge, and only on two areas, each about 1" long, almost directly across from each other. It's a shame, because I've found this particular lens to be quite good. I have another copy that is pristine, but I've compared images shot with both lenses of identical scenes and can't see any difference, despite the flaw in the one lens. Well built, but heavy enough to pound tent stakes with!

Also, if it's actually without lens creep as you state, it's a first for the A 70-210mm!
Sexy little big zoom, I have the M 80-200mm and just love that kind of lenses...

[Dewman]

Also, if it's actually without lens creep as you state, it's a first for the A 70-210mm!
Sexy little big zoom, I have the M 80-200mm and just love that kind of lenses...

Yep, no lens creep! I too have the M 80-200mm lens and I think it's highly under-appreciated. Sharp as the proverbial tack.... or at least mine is.... and the build, well that aspect of most Pentax-M lenses is well known.

[LensBeginner]

Yep, no lens creep! I too have the M 80-200mm lens and I think it's highly under-appreciated. Sharp as the proverbial tack.... or at least mine is.... and the build, well that aspect of most Pentax-M lenses is well known.

Yeah, sharp... a pity for all that PF, but most of the time the two things go hand in hand, esp. before the advent of ED lenses...