Leica M3 finder separation fix
The classic M2, M3, and early M4 finders used Canadian Balsam as optical cement. The Canadian Balsam over the decades has become brittle and dried out on the edge area, commonly referred to as “separation”. We do not recement the main prism, forcing the main prism apart is risky, and could result glass break. The 0.72 type finder in M2/4 separation happens on the main prism edges. The M3 finder has a different design, with two triangular prisms with silver coating in the middle, cemented together. There is a third prism, the front prism, which is a concave prism, cemented to the front of the main prism blocks to bring out 0.91 magnification. The common separation on M3 finder separation is not from the main prism in most cases, but the front concaved prism. We can recement the front prism, and make an M3 finder look perfect again. The two images show before and after.
