Minolta 50/1.4 AF spring mechanism repair

Maybe these pictures of disassembly and Repair of Minolta AF 50mm f/1.7 and f/1.4 Lenses by Pete Ganzel helps: https://pbase.com/pganzel/disassembly_repair_of_maxxum_50mm_lens

addy landzaat wrote: Maybe these pictures of disassembly and Repair of Minolta AF 50mm f/1.7 and f/1.4 Lenses by Pete Ganzel helps: https://pbase.com/pganzel/disassembly_repair_of_maxxum_50mm_lens

Thank you, I did look there first and it looks doable, but but with these drawings I never know how much to remove or the pitfalls in reassembly. I suppose I could buy one for parts and just swap out the mount.

Yes, I've tried that, thank you. I think I will have to take it apart somehow or risk spraying some dry silicone.

I know, late to the party. Hopefully you were able to resolve the issue. However, in case you didn't, here is my experience with this (50mm F1.4) and other Minolta lenses that have a sluggish aperture.

Assuming you didn't do so, I would recommend that if the aperture is still sluggish the best thing to do is disassemble and clean the individual blades in the iris assembly as well as the two plates of the assembly. This means to take the plates apart, remove all the individual blades, and clean each piece individually. I typically use a solvent like Isopropyl alcohol, methanol, acetone or hexanes (hexanes if the lubricant is silicone based) that will dissolve the lubricant. Depending on the oil, something like a dish detergent may be gentle enough to remove the oil. The advantage of solvents is that they will evaporate quickly, but if too aggressive may remove paint from the blades. Depending on the lubricant and solvent used it may take a couple of times to remove any residue. Make sure all parts are dry and debris free before reassembly. Any lubricant or debris in the blades are enough to cause a sluggish aperture, as it is designed to be clean and dry. Also inspect the blades for bends or damage, as that could be the culprit too.

I would make sure to take some good pictures of how the blades are lined up (although Pete does have some good one). The 50mm 1.4 is a fairly easy lens to repair. The most difficult part of the process is the reassembly of the iris. It is difficult to get the to overlap of the blades correct so you can fit the moving plate back on. However, once you have done it once, it does get easier once you figure out the little tricks in how to move the blades to align them.

I would also recommend that you use the lever on the moving plate to get a feel for if the assembly glides easily, binds, or if any residual oil is in the assembly as you actuate it several times both before and after assembly.

Thank you, I also thought that was a good video. My lens is not sticking in the blades, it is in the ring with the spring. If you pull the mount off, it sticks even when not attached to the lens.

Bob J wrote: I had similar on a beer can many years ago. There is a certain amount of interchangeability between some of the old Minolta lenses. I got the beer can going by using the rear bayonet and rings from a 35-70...

Good idea! Thanks.