Came back from a day of making photographs and was perplexed by what appeared from the eye as different densities from negatives of similar light from different shutters. It got me to think that it had to be something to do with the shutters because I had complete control of all of the other variables involved. As a result I pulled out my shutter tester that had been sitting idle in my drawer and went to work. The results set me back more than a bit but reminded me of a couple of things that I had forgotten.
First thing I needed to be reminded of is that the Ilex #5 is a piece of crap. Unfortunately, there are no other options in certain situations and we need to make the best out of the situation. Measurement of actual shutter timing proved this to be the case at the low end of the shutter scale (1 second and 1/2 second). The data shows me that I need to add 1/4 to 1/2 of an f stop to compensate for the inaccuracy of a couple of lenses including the one I used to make the photograph . Two Acme #4 shutters that I had not used in a while and assumed were functioning correctly were getting hung up at 1 second and are going back to have a CLA on them.
For the most part the more modern Copal #1 and #3 were within "industry" acceptable accuracy but the statistical range of the actual shutter times checking in groups of three test firings were all over the board. One speed would be high and the next speed up the scale the same percentage to the low side. A few shutters were consistently off by the same amount across the scale but that was the exception rather than the rule.
My feeling is that if you have more older shutters than new ones particularly Ilex #5's, it may be worth your while to do some evaluation of these with a shutter tester and allow yourself to compensate for this condition and monitor this situation so things do not get further out of whack. I am reminded of the age of axiom - the accuracy of the answer is only as accurate as the least accurate input.
In the back of my mind I kept thinking of the accuracy of my hand on the bulb of a Packard shutter and how well I could time a one second or longer exposure.
Food for thought...
Bookmarks