Tiny Specs on Front Optic

[mattbierner]

I recently got a Minolta MC W. Rokkor-X SI, 24mm f2.8 lens and am trying to identify the cause of some damage on the front optic. The lens is in almost mint condition and I suspect it spent most of its life, front optic exposed, in the clear plastic bubble case I found it in. But the front optic has a galaxy of little speckles on the exterior surface:




These specs resemble dust but cannot be removed with cloth, a dust blower, or even with some mild cleaning solution. They also feel as if they are etched into the front optic itself, as the surface is very slightly rough when I run my finger over it. The rest of the optics are perfectly clear.

Under a microscope, each spec almost appears to be a little bubble. I don't see the characteristic threads that would immediately mark it as fungus. Here's a crude video of two of the spots magnified: https://youtu.be/yDAypnbb4qs


Any idea what this damage is or what could have caused this? Coating damage of some sort perhaps? Or fungus?

Thanks.

[Lloydy]

Possibly damage to the coating, maybe sparks from fireworks or welding. I've seen a lens ruined / sacrificed by someone photographing sparks from an industrial grinder, but the damage was huge - a lot worse that your lens. ( He was using a broken Canon kit zoom lens to get a particular picture. ) but it wouldn't take much in the way of sparks to melt into lens coating.

[kds315*]

I had similar, caused by some sort of acid etching which had damaged teh coating.
Shoudl actually not have a visible impact on the resulting images.

[VLR]

You could put it under a microscope or take a close-up with a 1:1 macro and have a closer look. Could be many things, including speckles of spray paint...