william_ruzin

<p>Hi Andrew. I have to agree with Jerry here; the odds are that those 30 + year old aperture blades are sticky. I had a similar experience with my Vivitar 28-90mm, Series One ( Komine built) lens. After I had it CLAed, it worked fine. If I recall correctly, the Vivitar 28-90mm is prone to that problem. To check this, set the aperture at F16 and flick the lever on the mount side of the lens while looking at the response of the blades. The blades should move very quickly. Any hesitation is indicative of a problem. I have found the Vivitar S1 28-90mm to be a great lens, and worth the expense of a good cleaning. Cheers from Florida.</p>