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[OM] Re: f-stops (Was: Solstice web-site news)

Subject: [OM] Re: f-stops (Was: Solstice web-site news)
From: hiwayman@xxxxxxx (Walt Wayman)
Date: Fri, 21 Jan 2005 14:02:25 +0000
Well, to me, "lens opening" is synonymous with "the size of the hole in the 
diaphragm," a/k/a the f-stop.  Otherwise, that 4-inch lens with a one inch 
diameter would always be f/4 -- unless somebody's figured out a way to compress 
glass and metal so as to change the diameter.

Walt, aiding and abetting the counting of angels 

--
"Anything more than 500 yards from 
the car just isn't photogenic." -- 
Edward Weston

 -------------- Original message ----------------------
From: Moose <olymoose@xxxxxxxxxxxxxxx>
> Walt Wayman wrote:
> 
> >"The lens aperture is simply the diameter of the lens opening, expressed as 
> >a 
> fraction of its focal length.  Thus, a lens of 4-inch focal length with a 
> diameter of one inch has a relative aperture of 4/1, or 4.  the aperture 
> designation is expressed as f/4, indicating that the aperture is the focal 
> length/4.  Another 4-inch lens that has a diameter of 1/2 inch would be an 
> f/8 
> lens.
> >
> He also wrote earlier:
> 
> Moose,
> 
> I've never heard an f-stop defined by its relation to the front element.
> 
>   
> 
> Well, now you not only have heard of it, but are quoting it.  :-)
> 
> Moose
> 
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