I think this was a compliment. Anyway, I will consider it
one. FWIW, I consider the Leica shutter to be a very elegant
piece of engineering. There are those who will defend the Contax
shutter but the Leica design accomplishes the same purpose with a
much simpler mechanism. From an engineering standpoint that is
superior.
In its way the Graflex FP shutter is also elegant. Very
simple and rugged.
Part of the variation in effective exposure of the FP shutter
is diffraction around the edges of the slit. The sharpness of the
shadow cast by the slit on the film will depend on the angle of
the light striking it and the distance from the edge to the film.
Some old books will claim an FP shutter is more efficient than a
leaf shutter but it isn't. Its just that the lack of efficiency
comes from different places. Actually, a leaf shutter has
problems with diffraction around the shutter blades too. All
sorts of things happen. Since the effective f/stop varies as the
shutter blades open and close there can be variations in some of
the corrections but that also depends on the f/stop. When you get
into the complications its amazing any of this stuff works at
all. Not many things are as simple as they look.
On 4/29/2020 4:57 PM, Ken Hart wrote:
I enjoyed your third paragraph particularly: effective speed affected by cone of light, varies with focal length, focus distance, and so on. I considered writing a computer program and then creating a cell phone app to consider all this. Then I got to the part where you say "35mm cameras have much more sophisticated shutters", and realized I mainly shoot 35mm!
You also mention the variation in exposure top-to-bottom making skies appear darker, which Graflex advertised as desirable. An advertising mantra that would years later get picked up by computer software writers: "That's not a bug, it's a feature!"
All this made me think about old time portrait photographers. They posed their subjects, took the lens cap off, and counted "One-banana, Two-banana, Three-banana", and put the lens cap back on! They too decided the exposure was close enough.
Please keep writing- someday, somehow, this will all come up in a Trivial Pursuit game, and I'll win handily! When that happens, it will be because of you!
Ken Hart
kwhart1@xxxxxxxxxxxx
