Archived posting to the Leica Users Group, 1997/08/21
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>I have noticed an uneven exposure horizontally across the frame of pics >made with my M6 at the faster shutter speeds. I have had this problem >before with Nikons. I am going to do some tests with the M6 and two M3's. > >I plan to shoot an even blue sky area with a 90 mm lens at shutter speeds >from 1/1000 to 1/60. I will use T-Max 100 because it will give me a middle >gray exposure at 1/60, f:11 or so. > >Any ideas on the testing procedure or what to do once I verify problems. I wouldn't photograph the sky for this test. The sky on a cloudless day can vary in brightness. A 90mm lens should limit you to an evenly lit area, but I would photograph a backlit piece of thick white plexiglass instead. I routinely perform film tests by photographing backlit plexiglass in the stairwell of the building I work in. I have always gotten even exposures across the field of view, even with my 50 Summicron-M wide open. One day I had to use an interior wall when testing a fast film, and I got uneven illumination in the test negs. The wall looked evenly lit, but it wasn't. The film picked it up when my eye didn't. The point is that finding an evenly lit subject can be tricky, and the sky, with the possibility of high haze that isn't apparent to the eye, might be a bit too uncontrollable. Good luck, Charlie