Any Suggestions on How to Best Clean Dirty SLR Mirror on Pentax 67II?

Hi all,

I just did a random quick inspection of my Pentax 67II today. I took off the AE finder, took out the BA-61 focusing screen, and much to my surprise, found that the mirror was dirty. (The area that I circled in red in the attached photo of my P67II’s mirror is particularly irksome; it’s looks almost as if it’s a crusty-like substance.)

Is there a protocol on how to clean the mirror specifically on the Pentax 67II?

I know that these SLR mirrors are extremely delicate. Perhaps I’m wrong, but as I understand it, the reflective “crystals” (for lack of a better word) are on the very surface of the P67II’s mirror and aren’t shielded by any glass making this particular SLR mirror easy to scratch.

That said, do any of you more experienced photographers/repairmen know how I can best delicately clean this part of the SLR mirror, including which solvents to use (rubbing alcohol, ROR cleaner, Zeiss Lens Cleaner) and what materials to use (lens cloth, cotton swab, lens tissue), without scratching or otherwise damaging the mirror?

Any help on this would be greatly appreciated. Many thanks ahead of time!!!

DON'T put anything on it. Use a camel's hair brush and try to blow the stuff off at the same time. The good news is that what you don't get off, you can live with.

You can find info on cleaning SLR mirrors, do a search. And also cleaning digital imaging sensors. xkaes has the best approach- just don't. If I was still going to do this, I would probably use a piece of PecPad on a paddle like for cleaning a digital sensor. Eclipse cleaner. Damp, not dripping. Start at top and basically let the cleaning pad slide down the mirror. No pressing. Let gravity do most of the motion. A few swipes should cover the whole thing. And don't plan on getting it perfect.

All in all a risky operation with dire consequences if it goes wrong. If your 67II is working well, I would try other mirrors first. I imagine as with many SLRs that replacing a mirror is not simple.

No different than any other front-silvered mirror. Gently blow it with clean air first, then gently use whatever works best for your lenses. The biggest problem will be if there are little bits of old rubbery stuff stuck to it from the damper above.

Reflex mirrors are not in focus, meaning that small imperfections will not show up on the focusing screen. They do scatter a little light, but you really have to have a lot of schmutz on a mirror before it has a noticeable effect. Often the best thing to do is leave it alone.

The fragility of mirror coatings is somewhat over-rated by photographers. Amateur astronomers use first surface mirrors and regularly clean them. However, for an SLR mirror, since you can't take it out of the camera, it's probably better not to use liquids unless you've verified that they will dry off without residue. (Because if you leave a streak mark on a telescope mirror, you can try wetting the whole thing and cleaning it again; can't do that with an SLR mirror.) When I've been faced with a super dusty reflex mirror, I just clean it off gently with a soft brush or a very soft microfiber cloth.