Re: [photo-3d] ASA<->DIN

[Bob Wier <wier@xxxxxxxxxxxxxxxxx>]

>Bob,
>it's hard to de-cript
>> GN 50 ASA 25 DIN 15 in feet
>25°DIN=250ASA, 25ASA=15°DIN (film speed doubles each 3°DIN); so I should
>assume GN=50 (in feet) for 25ASA speed film.   that would mean GN=200 (in
>feet) for 100ASA, or GN=60.6 (!!?) in metric... hard  to believe in  an "old
>flash unit"... unless it uses singe-use bulbs.
>Sergio

Yeah - it's not real clear (bad translation from the Japanese?).
I'm ASSUMING that the GN if 50, since ASA 25 and DIN 15 would be 
reasonably equivalent.

>From other comments on the list, I'm inclined to think that maybe
I had it right that the GN for 100 ISO would be 100 - somewhat
weaker than a Vivitar 285/285.

I arrived at this number via the formulas at

http://minoxlab.com/dk051597/dkflash.htm

although it's not blindingly clear there, either.

THANKS

              Bob Wier
     mailto:wier@xxxxxxxxxxxxxxxxx
   4:01 PM Friday, April 7, 2000
        Unix/Internet Administrator
   Rocky Mountain College, Billings MT.
 keeper of the Photo-3d and Overland-Trails
mailing lists and the USA GPS Waypoint server



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