FP ISO 64000

Started 3 months ago | Discussions thread
xpatUSA
xpatUSA Forum Pro • Posts: 20,112
Re: FP ISO 64000

allineedislight wrote:

xpatUSA wrote:

Curious how the ISO steps have departed from doubling up each time, e.g. 100, 200, 400 ... and now have values like 64000 where the digits "64" are no doubt there for some reason - perhaps aimed at making some shooters feel comfortable - a bit like "ISO" itself!

... 800, 1600, 3200, 6400, 12800, 2560, 51200, ???, 102400 ...

well, just add 1/3 stop:

100, 125, 160
200, 250, 320
etc

52100 = 100*2^9 # 9 stops more than ISO 100

64000 is approx 64507 = 100*2^(9 +1/3) # 9 1/3 stops more than ISO 100

Good one.

Did occur to me and, yes, I already looked at 64000 versus 51200 - came to 0.32 steps but not a whole 1/3 to any self-respecting pendant.

... did I just say "whole 1/3" ?!!

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Pedantry is hard work, but someone has to do it ...

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