Manual focus lenses from the 1970s on usually have a mechanism to adjust the aperture during exposure so the lens can be held wide open while focusing to improve brightness. There is usually a pin extending from the lens into the mount throat or mirror box area. When mounting a legacy lens to a modern digital single lens reflex camera, this pin can sometimes contact surfaces in the mount throat, or possibly the mirror. It is dependent on the individual lens and camera model, so there is no general rule that applies.
Since I purchased my Olympus E-510, I've collected a number of Rokkor lenses for Minolta cameras (and a X-700, which is a very nice 35mm film camera): 50mm f/1.4, 58mm f/1.4, 50mm f/1.8, 200mm f/4.5, 45mm f/2.0 (This lens makes a very compact camera mounted to the 510 and I like the color and rendering quality of despite it being very inexpensive lens.) Due to the small viewfinder and lack of focusing aids, such as a split prism, microprism collar and ground glass I was used to in my film slr, I found it difficult to achieve critical focus reliably. Since I wanted to use the lenses wide open or nearly so, this was the case. The result is much better when using the lenses stopped down or with a larger viewfinder of the E-3, according to reports.
The aperture pin does need to be filed down for the E-300, E-330 (I posted a guide to Minolta Lenses on Four Thirds Cameras, covering this on ebay, the source information is the Rokkor Files page on Olympus). My experience is with the E-510 only, but I suspect it applies to all E-x10 and E-x20 series cameras, as well as the E-3 and upcoming E-30. I did have to very slightly file the aperture pin on my 45mm Rokkor. I used an emery board to remove the build up of enamel, which was sufficient for the pin to clear the lens mount throat. The pin cleared nicely without having to file the metal down.
All mount nicely without modification except for above. I believe the same would be true for the newer cameras. I do have to tighten the adapter set screw (This is a small hex screw that applies pressure to keep the lens tight to the adapter, since there is no lens mount locking mechanism as there would be on a Minolta camera.) for the heavier lenses, otherwise, they can unexpectedly dismount while turning the focusing ring (especially if the ring is stiff from age).
Since I purchased my Olympus E-510, I've collected a number of Rokkor lenses for Minolta cameras (and a X-700, which is a very nice 35mm film camera): 50mm f/1.4, 58mm f/1.4, 50mm f/1.8, 200mm f/4.5, 45mm f/2.0 (This lens makes a very compact camera mounted to the 510 and I like the color and rendering quality of despite it being very inexpensive lens.) Due to the small viewfinder and lack of focusing aids, such as a split prism, microprism collar and ground glass I was used to in my film slr, I found it difficult to achieve critical focus reliably. Since I wanted to use the lenses wide open or nearly so, this was the case. The result is much better when using the lenses stopped down or with a larger viewfinder of the E-3, according to reports.
The aperture pin does need to be filed down for the E-300, E-330 (I posted a guide to Minolta Lenses on Four Thirds Cameras, covering this on ebay, the source information is the Rokkor Files page on Olympus). My experience is with the E-510 only, but I suspect it applies to all E-x10 and E-x20 series cameras, as well as the E-3 and upcoming E-30. I did have to very slightly file the aperture pin on my 45mm Rokkor. I used an emery board to remove the build up of enamel, which was sufficient for the pin to clear the lens mount throat. The pin cleared nicely without having to file the metal down.
All mount nicely without modification except for above. I believe the same would be true for the newer cameras. I do have to tighten the adapter set screw (This is a small hex screw that applies pressure to keep the lens tight to the adapter, since there is no lens mount locking mechanism as there would be on a Minolta camera.) for the heavier lenses, otherwise, they can unexpectedly dismount while turning the focusing ring (especially if the ring is stiff from age).
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