I just peformed a ss test on 7 LF lenses. There has been several posts asking a bout the Calumet ss tester. For the money, $80, I was very impressed by this li ttle gadget. More importantly I was very impressed with the results. I tested 7 new LF lenses, ranging from 75 to 600mm, and between 1/2 second and 1/500, the furthest reading off was about 5%, or less than 1/10 of a stop. And that only occured a few times. All in all, things tested almost perfect... In this field, I find that hard to beleive, could have I screwed the tests up? I checked my m ath several times... anybody ever try this?