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Forum: Troubleshooting and Beginner Help
09-03-2015, 02:51 PM
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I have seen some of these for sale with oil on the aperture blades which would be consistent with the symptoms. You can access the aperture blades by unscrewing the beveled trim ring around the front element. Some kind of friction tool, like a sink drain stopper, should grip the thing well enough. Then you'll see a brass colored ring with three tiny screws in it. My Moody's JIS #000 fits these. They were a bit tight. The ring holds on the front lens group so don't tip the lens to let the screws fall out without holding the group in. Once the group is removed you can see the top side of the aperture blades. I have had reasonable luck carefully wiping them down with mineral spirits or naptha, then drying them off, several times, using the aperture lever to move them and distribute the solvent. The blades are thin metal so you can't press on them. When the solvent is dry, try the aperture lever again and see if the blades snap closed properly. You should check the inner lens surfaces of rear and front groups to see if either has oil or solvent on them, and clean that before reassembly.
Sometimes I have to remove the rear lens group to clean the other side of the blades. The oil migrates everywhere so the ideal repair is to remove the blades, wash them and the area in solvent and reassemble. That usually means a lot of disassembly since the aperture mechanism is right at the heart of the lens.
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Forum: Troubleshooting and Beginner Help
08-31-2015, 07:21 AM
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The EXIF says spot metering was used. The camera would have to be using the exact same "spot" for these shots to meter the same. I think that's at least a contributor.
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