Archived posting to the Leica Users Group, 2003/04/05

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Subject: Re: [Leica] Alternate to current 35mm ASPH?
From: Martin Howard <mvhoward@mac.com>
Date: Sat, 5 Apr 2003 22:19:17 -0800

D Khong wrote:

> Now I am itching to ask,
> How do you arrive at the gain in two stops?

50mm f/2.0.  Largest aperture: f/2.0.  Slowest usable shutter speed: 
1/60s (or 1/30s).
35mm f/1.4.  Largest aperture: f/1.4.  Slowest usable shutter speed: 
1/30s (or 1/15s).

The shorter focal length typically lets you get away with one stop 
slower shutter speed.  Total gain = two stops.

M.

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