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Re: [OM] Sunny 16?

Subject: Re: [OM] Sunny 16?
From: "John Hudson" <jahudson@xxxxxxxxx>
Date: Tue, 22 Jun 1999 07:15:56 -0700
-----Original Message-----
From: Chuck Norcutt <norcutt@xxxxxxx>
To: Olympus mail list <olympus@xxxxxxxxxxxxxxx>
Date: Monday, June 21, 1999 7:00 PM
Subject: Re: [OM] Sunny 16?

snip

>
>I'll go just a bit further and assert that this is actually where our
>film speed ratings come from.  The ISO rating is the inverse of the
>correct shutter speed using the "sunny 16" rule.  An ISO 400 speed film
>will yield correct exposure under bright sun at f/16 with a shutter
>speed of 1/400 second.  Fortunately, the ISO rating is based on the old
>ASA standard and not the DIN standard.  The DIN number was "just a
>number".  It didn't have a useful meaning like the ASA/ISO value. Now
>the young whippersnappers will have to ask: "What's DIN?"  "What's ASA?"
>
>Chuck Norcutt
>Woburn, Massachusetts

OK older whippersnappers.  Wasn't there a Scheiner [sp?] rating system at
one time before DIN and ASA were invented?

jh


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