Can anyone explain the formula for calculating and calibrating a shutter. The copal 0 shutter on my schneider 72mm xl is dead and beyond repair, i have copal 0 on my 90mm nikon SW, and so will try and use it between the two lenses on my shoot tomorrow/this weekend. I'd like to calculate a temporary scale for when i use this shutter on the 72mmxl temporarally....

Also does anyone have a copal zero with reliable shutter speeds for sale!

thanks

Dan