hazy mirror on SLR

[David Lyga]

I have a Minolta SR-T that at one time must have been stored in a very humid environment because the mirror has a permanent and pervasive, rather thick haze. Of course, I tried to clean it but the haze is ingrained. I even tried Naval Jelly and Numisol but nothing works.

What surprises me (and founds the purpose of this post) is the amazing fact that when looking through the viewfinder with a normal lens, the viewing image looks neither less contrasty nor less sharp than the viewfinder of a different SR-T with an intact mirror. Why is this? There is no physical damage to the mirror but the presence of the rather thick haze does annoy me.

This is a 'later' edition of the SR-T and, unlike the first ones, there are no screws clamping down that mirror making a changeover rather easy, Instead, it is firmly glued down and I do not wish to take a chance of cracking it in my efforts to change it. But ... so what? Again, the viewfinder image is really indistinguishable from one using a 'good' mirror.

Thoughts? - David Lyga

 

[BrianShaw]

I don’t understand... I would think that Naval Jelly and whatever rubbing accompanied would have completely removed the mirror surface.

 

[Wallendo]

I suspect that the haze is only noticeable when the lens is removed and the mirror subjected to direct light. When looking through a viewfinder with a lens in place, the irregularly reflected light is dispersed away from the viewfinder and therefore not visible. All light coming through the lens is somewhat collimated by the lens (even when out of focus). As a result, rays which are dispersed are likely to hit the sided of the camera, not the viewfinder. The "thick haze" is likely only reflecting a small portion of the light hitting the mirror, so the viewfinder appears equally bright.

 

[David Lyga]

Yes, gentlemen, I am adept at cleaning mirror, but this one has a haze that does not budge. Wallendo, your description is really comprehensive and understandable. Apparently, what one sees 'directly' might not fully impact what one sees 'indirectly'. The 'important light rays get by in both instances and I do find that fact rather interesting. Thank you all. - David Lyga

 

[Scott Micciche]

Try hydrogen peroxide for a minute or two, then finish with some lighter fluid. My Minolta SRT 101 is not a first path mirror, it has some thin glass layer. I use a pec pad wrapped around a q-tip for this work.