Just made a shutter tester out of a $1.50 infrared photocell from RadioShack and my computer's sound card. Tested my Speed Graphic lenses. My 90 Optar measures too fast in most settings (.736 at 1 sec. and 1/50th right on). My 135 Optar measure slow (1.3 in 1 second and pretty accurate for the other speeds. My newly purchased 210 Rodenstock in Copal was very accurate at .905. I couldn't accurately measure the top 1/400th speeds of the shutter as they showed the same speeds as the 1/200th settings. Now for the fun part. I measured my focal plane shutter which i have never ussed. The 1/30th was off almost a stop slow but the rest of the speeds were more accurate than the leaf shutters and It seems I could accurately measure the 1/500 speed but not the 1/1000 speed. The test revealed why some of my Velvia film came back underexposed with the 90 lens. The 1/25th was especially fast and that would be the speed used in full brightness situations.
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