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Author Message   Glenn Tinkerer Username: Glenn Post Number: 1016 Registered: 07-2006 Rating: N/A Votes: 0 Posted on Sunday, June 10, 2012 - 02:18 pm:    The lever on the back of the lens allows the iris mechanism to be locked, so the iris can be worked manually with the lens reversed or off the body and mounted via extension rings etc. For auto iris on the camera, set the lever to the white dot. To lock the iris mechanism in manual, push the iris operating 'lever/tab', that sticks out from rear of lens adjacent to the lock lever, towards the lock lever and then move the lock lever to the red L. Not sure about the shutter release situation,but be aware of the following - In the FTb it is possible to lock the manual stop-down lever (self-timer lever pushed towards mirror box and small lever below it set to red M) in the manual position. When this is done and the lens removed, you can see a red dot in the bottom right corner of the mirror box, just adjacent to the vertically moving aperture value sender lever for the meter. If memory serves one should not see the red dot when mounting auto lenses, so make sure the camera manual stop-down lever is not locked. Red dot is covered by camera iris operating lever when camera set to auto iris mode. If you are saying that new lens works on one of your original bodies and that the new body works with one of your original lenses, I do not know what to suggest. I would get sight of the FTb instruction manual and make sure everything is set right before you really start worrying.