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28MM AE Lens on RX Incorrect f Stop Indexing


New Member
I am new to the forum,but I hope someone can shed some light on my propblem. I purchased this 28MM AE lens 2nd hand. The problem is that when the lens is set to f22,16 or f2.8 the RX viewfinder reads correctly. When set to f4 it reads 3.5, f5.6 reads 4.5, f8 reads 6.5. This does not happen with the 50MM 1.4 lens or a 70-210 Vivitar c/y mount lens,only the 28MM AE. I feel the lens is malfunctioning,or is this normal for a AE lens on this camera. This occurs also in the Av setting also. Even though the viewfinder reads different from the lens;I am sure the lens apeture is correctly set. Otherwise the lens is good. Can this be repaired for a reasonalble cost, or would I be better off looking for another lens? Am I right that the lens is indexing correctly in fact,but just with a bum read out. Thanks for your help


From what I understand the aperture is communicated to the camera through a small lever that moves as the aperture is changed. I have had some difficulties with my ST and a second hand 85/1.4 It shows it as a half stop faster (i.e., 1.2 when set at 1.4). It seems that the contact between the lever and the camera has different tolerances on different bodies. It works fine with my RTSII. I tried to change the bayonent mount (an easy process), but no avail. There have been other threads on this forum about this, so you may want to check them out. Just take some slides at the affected aperture and the non affected aperture (using appropriate shutter speeds) and see if there is a difference in exposure. If so, then you will probably need to get fixed or service. If not, then it is only a cosmetic problem, and can probably be overlooked. Hope it helps, David.