Lens cleaning

EBC Fujinon 28/3,5 was disassembled in parts to remove sticky old lubricant in iris control ring and iris module inside, also undesirable mold should be removed in the lens inside at the same time. As usual, metal lens case make it possible to perform periodical maintenance as to original condition. Uninvited guest to the lens mechanism often appears in the most inconvenient portions unfavorably. Lens overhauling procedure remind me of special techniques and memories that I had forgotten.
Methyl alcohol-Ether mixture solution would be used for lens surface cleaning, the ration is 3:7 though factory engineer recommends 4:6, the reason is the humidity in the room air, the solution is called as Ether. The centricity of the lenses should be confirmed when being assembled in position, because the center displacement of the element does harm on the performance of the lens. It is often the case that the lens case accuracy is not enough as to affect the assembly tolerance, thin layer of adjusting sim is put around the round surface to compensate the unnecessary space to establish the centricity of the lens piece. As the lens pieces themselves are finished well promptly, this kind of tiresome adjusting when re-assembled is effective to obtain the designed original performance. Lens outer round surface and the supporting case should be fit well like piston and cylinder of the motor of mobiles. The lens for large format is engineered so especially those made in former West Germany.