Just bought one of these sight unseen and it's got heavy oil on the blades. How difficult is it to disassemble to get at them to clean? Any help would be greatly appreciated, the rest of the lens is in great condition so this is a bummer.
Unfortunately, you may have to take the lens all the way down to the "aperture cup", with the aperture blades at the bottom of the "cup". The top and bottom lens assemblies will need to be unscrewed CCW from the "cup" to get at the blades. There is a ring that holds in place a disk, that holds the blades in place. The blades have 2 round plugs that fit into holes in the disk, which when rotated will open and close the blades. BTW, its not good enough to soak the "aperture cup" in solvent as they need to be bone dry (soap and water). Well, I guess you could try a solvent soak, but its a compromise.
I don't have alot of photos of the process, but if you decide to go forward, I'll take a look.
Just use it as-is, I'd say, unless there is oil on the glass. Slow blades won't matter for alt use, as it's usually stopped-down when shooting anyway. Slow blades (due to oil) only really matter when they snap open/closed as used on the original equipment film bodies.
Why you have to clean them when you use the lens in stopdown mode, your only choice with EOS. Unless you few they are annoying.
Once again, if it aint broke...
The oily blades usually comes from seepage from the wrong helical grease that is adjacent to the aperture area, or plain negligent service of the lens.
Eventually, the blades may freeze or depending on the oil, outgassing could cause harm to the lens surface.
I shoot a manual focus lens partly because it fills a vacancy in a stable of lens for my EOS. But mostly because there's a bit of nostalgia going back to me being in control of the capture process - focusing and selecting the moment for the exposure. All of that gets lost if I have to do it with a dirty, oily, and bgn gear. Gear that has been restored, repaired, CLAed is OK. Even brassing can be a badge of long and honorable service. But oily aperture blades? It's like going to the Memorial Day parade in a dirty and tattered uniform.
-Steele
Either that, or the lens gets left in a car on a hot sunny day
JimBuchanan wrote:
Good practical points on stopdown mode use.
The oily blades usually comes from seepage from the wrong helical grease that is adjacent to the aperture area, or plain negligent service of the lens.
Eventually, the blades may freeze or depending on the oil, outgassing could cause harm to the lens surface.
debuggerus,
Thank you for posting the images of disassembly of your 85 Rokkor. I need to do the same thing to my 58 1.4. Your images gave me the encouragement to attempt it. Then I will finish installing Jim Buchanan's adapter. When I started installing the adapter the aperture was a little stiff but appeared to be dry. Then it set on the bench with the mount off for a few days and when I was able to get back to it oil was visible on the blades and it was near frozen open. I'm not sure why. Could anyone say where to find the proper lube for the helical?
Steele
