Earlier this year, I bought an interesting set of 3 Vivitar extension\ntubes for my FM3a that can best be described as "semi automatic". I\ncould compose and focus with the lens aperture full open, then the\nblades would snap down the instant the shot was taken. So they were\nautomatic in this respect. But the camera's meter didn't know what\naperture the lens was set to. I had to do "stop down" metering or use\na hand-held meter. Another thing was that the smallest of the 3 tubes\nrefused to screw onto the FM3a, so I could only use it in combination\nwith another tube.\n\nAnyway, the tubes were recently stolen. I will need to replace them,\nbut I think I'll stay away from Vivitar unless they have a set of\nbetter tubes. Has anyone else seen this type of behavior? Thanks.\n\nBob C.