Can SMC be mistaken for optical separation in a Pentax lens?

[robertverhey]

Hello all.

I just sold a Pentax MX, about 25 years old, and the buyer returned it, saying the lens (SMC 40mm 2.8 Asahi Pentax) had optical separation, or the lens layers had started to separate. He said he could tell this because there were "rainbow-like" shades when you look at the lens. I now have the returned camera, and have had a look. While I can't see any rainbow shades, there does seem to be some sort of coating, not unlike that which is applied to my spectacles, a non-reflective treatment.

I can't imagine what would make the lens components separate.... it certainly looks intact and takes great photos.

Just wondering, is it possible he has mistaken this SMC coating for separation?

Hope someone can assist

Robert

[thazooo]

Could be a mistake, a rainbow shade across the whole lens is it's coating. Separation may show it at the edges.
Along with white spots or lines. You can determine this by looking through the lens for separation or across the lens
for normal smc rainbow. Here's a link to an interesting article concerning lens faults. Simple with no examples.

http://www.photoethnography.com/Classic ... ~mainFrame

[robertverhey]

Thanks for assistance, a very useful link too