Archived posting to the Leica Users Group, 2001/05/16

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Subject: Re: [Leica] 180mm comparisons
From: SthRosner@aol.com
Date: Wed, 16 May 2001 11:41:34 EDT

In a message dated 5/16/01 11:22:00 AM Eastern Daylight Time, 
icommag@toad.net writes:

<<  why are cinema zoom lenses so much faster
 than for still cameras? I have three Angenieux cinema zooms, all quite fast.
 For example my 9.5mm to 57mm is a f1.9, my 16mm to 44mm is f1.3. >>

How large is the film area these lenses are required to cover? Answer to your 
question is your lenses are corrected to cover a much smaller image circle 
than the 35mm format - 24X36. It's far easier (and cheaper) to compute a 
lens, whether fixed focal length or zoom, to correct aberrations to an 
acceptable level in a small image circle than a large one.         

Seth Rosner     LaK 9      

Replies: Reply from Mark Rabiner <mark@rabiner.cncoffice.com> (Re: [Leica] 180mm comparisons)