Zenit B upgrade project

[themoleman342]

I know most people in this forum are over the Zenit E-series and prefer either the spotmatics, fujis, prakticas, or any of the other various metal SLRs from the 70s but I figured I'd share this anyway. For awhile now I've been slowing upgrading my Zenit B to be more reliable in the field (re-lubing, painting internals flat black, re-sealing around prism/back, replacing ground-glass) so I'm always looking for new things to do. Zenits take quite a bit of flak for having dark viewfinders so I was hoping to devise a workable solution. I decided to take a mathematical perspective and break-out the middle-school geometry.

The average Zenit mirror has a surface area of roughly 672 mm sq (Top
being about 28mm, side 26mm, and each cut away having a base of 16mm height of 3.5mm = (28mmx26mm)- 2((1/2)(16mmx3.5mm)) = 672 mm sq. I noticed that the mirror housing actually allows for a square mirror with the dimensions of around 31mm x 26mm which is 806mm sq. (there is quite a bit of unused space around the original one) So now subtract 672mm sq from 806mm sq which equals 134mm. Now divide 134mm by 672mm. You come up with .199 which is 19.9%. Which actually means that there is about a 20% gain worth of surface area over the older mirror. I have unused front surface mirror of the same thickness that I used to replace my ikoflex mirror with. So I was going to cut from that.

Does anyone have any thoughts? I'd rather not get back answers to the effect of "just buy a spotmatic" but I would really love and appreciate other insights or advice. Thanks!

~Marc