I just got into medium format photography about two months ago after shooting 35mm for about 14 years with a Bronica SQ-A, an 80mm S lens, and a metered prism. I've been quite happy with the results so far but I've got a couple of questions: The shutter speed dial on the metered prism appears to override the shutter speed selection on the camera body. I tested that by setting a short exposure time on the body and a longer one on the prism and the longer one prevailed. My question is about the half increment adjustments in shutter speed the prism's dial has which aren't present on the SQ-A camera body. Since the prism appears to override the camera body, does it provide the half step shutter speed increments or should I adjust it in full increments only (i.e. are the half steps only available when used on the SQ-Ai, for example)? I'm planning to buy PS series lenses for other focal lengths but is the quality difference between the S and PS series great enough that I should consider replacing the 80mm/f2.8 S lens I have now with an 80mm PS? One last question: is it possible to mount other manufacturers lenses on the SQ-A either directly or with an adaptor?