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macandal
19-May-2014, 16:40
I got a Crown Graphic (4x5) that came with a Graphex 135mm f/4.7. Starting with that "odd" (to me) aperture, 4.7, this lens also has different shutter times than I'm used to. After 1/2 of a second it jumps to 1/5 then 1/10 then 1/20, 1/50, 1/100, 1/200, and 1/400. So, how am I to use these "new" times? If my light meter gives me a reading of f/4 at 1/4 am I supposed to use f/4.7 at 1/5 or how does that work?

Thanks.

ic-racer
19-May-2014, 17:01
I got a Crown Graphic (4x5) that came with a Graphex 135mm f/4.7. Starting with that "odd" (to me) aperture, 4.7, this lens also has different shutter times than I'm used to. After 1/2 of a second it jumps to 1/5 then 1/10 then 1/20, 1/50, 1/100, 1/200, and 1/400. So, how am I to use these "new" times? If my light meter gives me a reading of f/4 at 1/4 am I supposed to use f/4.7 at 1/5 or how does that work?

Thanks.

I think the most successful way to proceed in these cases is the measure the actual shutter speeds and go from there.

This is a link to fractional shutter speeds (1/3 stop).http://imageliner.blogspot.com/2011/11/fractional-shutter-speed-and-aperture.html

BrianShaw
19-May-2014, 17:48
I round - it works just fine.

John Koehrer
23-May-2014, 16:58
In the situation you're in, 1/5 @ 4.7 you're underexposing by about 1/2 stop.
f4->5.6 is one stop and 4.7 is roughly 1/2 stop from f4.
the older speeds vs newer are pretty much a wash because of tolerance in the speeds. To convert them,divide 1000ms by the speed selected like the examples.
1/5= 200ms, 1/4 = 250ms
1/10= 100ms, 1/8=125ms
1/20= 50ms, 1/15=62ms

You can pretty much guarantee you're not going to find a shutter that is 100% accurate at any speed but some people have had theirs set so they have one or two that are accurate. Usually at the slower speeds, high speeds on a leaf shutter are estimates.

jbenedict
23-May-2014, 20:40
Some paste a chart onto the lens board which describes the actual shutter speed in relation to the marked speeds. I usually just round it and call it good. It can make a difference with transparency film but it doesn't seem like a big deal with negative stock.