Just got a shutter tester off of Ebay as a first step to tightening up my exposure and processing. My lenses were pretty good up to about 1/60, OK at 125, and quite slow at 250/400/500. Interestingly, the most accurate across the board is a Linhof Symmar/Compur that is about 60+ years old. Since I shoot Tmax 100, I am never shooting about 1/60, so the faster speeds do not matter.

Got to thinking about aperture and wondering if the shutters are really slow. As the speed increases, the time spent opening and closing increases as a fraction of the shutter speeds. Since you test at small apertures, you get the longest speed. But I suspect that if you had the lens wide open or down a stop or so, and you measured the total light through, you might find that a shutter speed that measures slow is correct when you look at the total light, as you would for an exposure. So if you use a small aperture to compensate for the slower speed, you get an under exposed negative.

Thoughts on this?