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Re: [OM] Brigher Viewfinders

Subject: Re: [OM] Brigher Viewfinders
From: "Tom Scales" <tscales@xxxxxxxxxxxxx>
Date: Tue, 26 Dec 2000 10:58:24 -0600
Yes, I was backwards....duh.

Tom
----- Original Message -----
From: "Mark A. Thalman" <mthalman@xxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>; "Tom Scales" <tscales@xxxxxxxxxxxxx>
Sent: Tuesday, December 26, 2000 10:53 AM
Subject: Re: [OM] Brigher Viewfinders


> Tom Scales wrote:
>
> > I'm confused.  I thought one stop was the square root of 2 brighter
(about
> > 1.4) and TWO stops was twice as bright.
> >
> > Am I missing something?
>
> You just have it backwards.
>
> One Stop is twice as bright.  To double the area of a circle you multiply
> the diameter by the square root of two.  The increase in brightness is a
> power of two.  A two f-stop increase is 4 times the light (2*2).  A three
> f-stop increase is 8 (2*2*2) times the light, etc...  To achieve a one
> f-stop difference with a starting aperture of 1.0 the diameter needs to be
> multiplied by 1.4 (the square root of two).  To achieve the f-stop you
> divide the diameter of the diaphragm by the focal length.
>
> Clear as mud now?
>
> --
> Mark Thalman, markt@xxxxxxxxxxxx
> f u cn rd ths thn u cn gt gd jb prgrmmng cmptrs
>


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