thrice wrote:
is the mirror silvered on the top surface? If so, the vinyl I have is adhesive backed - it might peel off the silver, not what I want.
It's a very good bet that the mirror is front surface. Otherwise the unsilvered face, even if well multicoated, would cast a slight double image up into the viewfinder. Coatings are routinely applied on top of the aluminum to reduce oxidation and improve reflective properties, but I wouldn't rely on much mirror surviving after a gum adhesive is cleaned off.
I guess this might make sense if you were only going to use manual focus alt lenses and nothing else. In my case I will always be using EF lenses alongside the alt lenses I have adapted.
Sounds risky but interesting. I guess one of us kids will have to jump in the deep end and tell us how the water is...
I got curious and did some googling. Apparently the 1970s russian Zenit cameras had back-silvered mirrors. As far as I know all other SLR mirrors are front-silvered. The focus accuracy depends on critically small tolerances to keep the optical path length exactly the same lens-to-sensor as lens-to-mirror-to-focus-screen . I don't know, perhaps if you changed the mirror thickness could you compensate by shimming or thinning the focus screen?
