[none]

[James Michael Lennon <lennon@atlantic.net>]

Date: Fri, 24 May 2002 11:48:36 -0500
From: "Steve LeHuray" <icommag@toad.net>
Subject: Re: [Leica] How does the Leica R8 calculate exposure in 
matrix metering mode?
Message-ID: <200205241553.g4OFr6P22445@hermes.toad.net>
References:

Steve LeHuray wrote:

"....not meaning to be facetious here, but somebody please help me
understand all these different metering modes that are available on
state-of-the-art modern cameras.

As I understand it, for example, you make an exposure, let's say 250th at
f8.0. What confuses me with so many different internal metering modes, how
does any of those different modes improve upon 250th at f8.0?? I am grateful
for any explanation."


Steve,

You are absolutely correct.

If you properly decide that the exposure is F8.0 at 250 sec., the 
best any meter can do is match it. I am speaking here about a 
photographer working with available light.

The camera can't know what it is looking at, so it takes a general 
reading which it arbitrarily imagines to be "average" and sets the 
aperture and shutter speed to allow for an average scene. If it is 
more or less an average scene, the film latitude will cover any 
mistake the meter makes.

What is a real improvement (for those very rare times when using a 
camera in an automatic mode makes sense) is the matrix metering that 
someone described previously in the discussion group. For example, 
let's say you only have one arm and so can't meter off your hand to 
get the correct exposure and you are at the beach shooting toward the 
water. This is a perfect time to let the matrix metering do its 
guesswork.

Matrix metering = pretty darn good at correctly exposing backlit 
subjects, i.e. almost as reliable as any basic photographer who 
learns to meter manually. The only exception to this is when you 
can't meter your hand in the same light that is falling on the 
subject. At those times you need a spot meter to meter off something 
in the scene that is equivalent to your hand or a grey card or 
something else that you can reliably use to set the exposure.

Another legitimate use for using a camera on automatic is this. You 
travel with your camera turned to automatic mode at all times. 
Something amazing happens, you whip-out your camera and fire away 
without stopping to take a meter reading. You hope it is an average 
scene, or that the film has enough latitude, and/or you have matrix 
metering.

Of course, using a camera on automatic is great when you hand it to 
someone who know nothing about photography (meaning they don't know 
the three things you need to know...how to set the aperture, shutter 
speed, and focus) and let them shoot away in auto focus mode.

Jim


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