Quote Originally Posted by Dan Fromm View Post
Jim, I agree completely on the first point.

Y'r second point puzzles me. Why do you think that erratic measured shutter speeds, if that's what your problem has been, are due to an erratic shutter timer instead of an erratic shutter or variations in your measurement procedure? ..............
Because, after I got such discouraging readings, I took the tested shutters to a professional camera repair shop and had them speed tested. They confirmed both that the slower speed readings were relatively accurate and that the higher speeds had been misread by my testers. Which was exactly what my film tests had indicated.

The testers I used were of two types ... photo-cell (supposedly measuring the amount of light passed) and sound card (measuring the time between opening and closing of the shutter ... which, of course wouldn't be appropriate for testing an FP shutter.) I even made sure I was using the correct light intensity at the recommended distance if such was listed. All, including the Calumet, were close at low speeds and increasingly off above 1/100.

I still use one of the photo cell testers because virtually all of my shutters max out at 1/125 or less ... except for a couple of 1/300 Optimos ... which might, on a good day reach 1/150 on the 1/300 setting.

Since I only have two FP shutters ... a 4x5 Speed Graphic ... and an 8x10 Folmer Graflex ... it makes sense to just do a speed test on each with film ... and those results will apply regardless of the lens I'm using.

Focal Plane shutter time testing is an interesting subject ... but, as my grandfather used to say ... “It is a long road to a small house.”