Practical answer does not equal flippant answer.
Practical answer does not equal flippant answer.
Thanks Mark. I appreciated this.
The only trouble with doin' nothing is you can't tell when you get caught up
Actually, you are solving the quartic equation
x^4 + x^2 - x = 0
There are four roots. two of them are complex. None of them are the forth root of two.
I prefer to just write out the sequence
Best wishes --- Allen
1/2 stops calculate by factor 2^(1/4)
1/3 stops calculate by factor 2^(1/6)
1/2 stops: f/1 f/1.2 f/1.4 f/1.7 f/2 f/2.4 f/2.8 f/3.4 f/4
1/3 stops: f/1 f/1.12 f/1.26 f/1.4 f/1.6 f/1.8 f/2 f/2.2 f/2.5 f/2.8 f/3.2 f/3.6 f/4
1/2 stops: f/4 f/4.7 f/5.6 f/6.7 f/8 f/9.5 f/11 f/13 f/16
1/3 stops: f/4 f/4.5 f/5 f/5.6 f/6.3 f/7 f/8 f/9 f/10 f/11 f/13 f/14 f/16
1/2 stops: f/16 f/19 f/22.6! f/27 f/32 f/38 f/45 f/54 f/64
1/3 stops: f/16 f/18 f/20 f/22.6! f/25 f/28 f/32 f/36 f/40 f/45 f/51 f/57 f/64
1/2 stops: f/64 f/76 f/90 f/108 f/128
1/3 stops: f/64 f/72 f/81 f/90 f/102 f/114 f/128
This has been an academically interesting discussion, but our LF lenses are so likely to have inaccurate shutter speeds that FAPP I would ignore 1/2 F-stop nuances.
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I doesn't hurt to try and be a little more accurate. I have a shutter-speed tester that I use to find the actual speeds on all my shutters and then label the lensboard with speeds to the closest 1/3 stop. I then use intermediate aperture settings, also in 1/3-stop increments to get my exposures as close as I can (while being aware that there is an inherent margin of error in the system).
FWIW, a whole stop underexposure with transparency materials will yield an unusable slide... even a half-stop is pushing it. Striving for accuracy in exposure is the only way to get even close. Ignoring a half-stop "nuance" that is compounded by other errors in the system can result in severe exposure problems.
One-third-stop increments are how my meter reads, how film speeds are indicated and how filter factors and graphs of curves, etc. are marked. I see no reason to use half-stop increments instead, although it's interesting to know.
Best,
Doremus
Same here, except I've not tested my shutter speeds. My meter is set in thirds and most of my lenses are marked in thirds. I just do not sit down and calculate or try to remember the approximation for the actual f/stop number. I'm happy with keeping that in the black box.
David
hell.. as sloppy as I am with my development times... a third stop here or there taint pis
Square root of the square root of 2 = square root of 1.4142 = 1.1892
either divide or multiply to go down or up. It is proportional to the area of the lens which increases with the square of the radius.
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