I recently bought a well used copy of the Pentax-M 100 mm macro lens and I noticed a strange "net" behind the front element:
I tried to find a proper picture in the net to verify if it's normal for these lenses but failed to find one. There isn't such thing in any other of my Pentax-M lenses so I assume the lens was dismantled/repaired and it is some king of glue or tape to keep the front element together with the rest.
Am I right?
The lens performs well or so it seems, I didn't notice any major softness or light fall off that could be a result of this "net" inside, but still it worries me a little bit ;-)
TIA for any hint.