Mamiya 7: Cracked Frame Finder Glass Replaced with Dichroic Glass
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This Mamiya 7 came into the shop with a cracked frame finder glass. This is a good time to replace the original style plain groundglass window with the Mamiya 7II style dichroic glass that gives the frame finder lines a yellow cast.
Photo two shows one part of the glass fabrication process of using an abrasive to frost the back of the window. The third photo is of the newly installed window.
I don’t usually recommend installing a new style window unless the old one is cracked and needs to be removed. It’s a bit of labor involved for a small change: yellow frame lines.
The other issue on this camera was that the lens has residue inside the front and rear element groups and this turned out to be issues between cemented elements. This was not fixed as there is no easy solution. When buying these lenses, especially ones produced from 1995-2000, it is a good idea to lock the lens open on “B” and shine a small light through the lens for inspection.
This particular lens had some attempt at repair/cleaning in the past judging from the damaged retaining ring seen in the fifth photo. And, seen in photo six is how far off the rangefinder cam was on the lens, +0.10mm. No way it came from the factory like that or that is is normal wear. The Mamiya 7 lenses are not the ideal candidate for DIY repairs as they require proper tools, test equipment and experience to maintain at factory specs.
