After 5 year missing the filter calculation, I finally get around how to do the calculation (even though it is not that unclear in the original description in the book Examples - the making of 40 photographs or here
http://www.anseladams.com/content/an...ancedotes.html
- ISO 64 for a moon at 250 c/ft2 mean f8@ 1/250s for zone V.
(exposure calculation Example p. 174-175;
which meant EV 14-2/3@ISO100 or EV14@ISO64)
- to zone VII the moon is now at f8@1/60s
- filter is Wratten No. 15 (G) filter with filter factor 3
(See http://www.kodak.com/US/plugins/acro...h2_filters.pdf Kodak said filter factor 3 means 1-2/3 additional stop is required.)
it will be f8@1/20 or f32@.8s approx. f32@1s used by Ansel
The only one remained not sure is how the lens is being used. I have a cloned triplet and I am not sure which element is being used (the back one?) and how it was placed (in the front?)
BTW, the Moon and Half Dome (p.133) use 400 c/ft2 by adding 150 c/ft2 sky on top of the moon 250 c/ft2 with filter factor 4 (or 2 stop).
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