Archived posting to the Leica Users Group, 2009/01/19

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Subject: [Leica] Question about M8 exposure
From: henningw at archiphoto.com (Henning Wulff)
Date: Mon Jan 19 12:02:03 2009

I sent the following message a couple of hours ago, but it got hung 
up somewhere. So here it is... It'l probably pop up some time, out of 
some bit-swamp again later.




>Even when using an incident meter I find there is often scope for
>over-exposing to move the histogram to the right.
>
>And to reply to Mark, it depends on how you define over-exposure. I define
>it as giving more exposure than the meter indicates. If you define it as
>blowing out the hightlights then you are correct, but I don't think that's
>what most people mean by over-exposing.
>
>Bob
>




'Over-eposing' means exposing more than should be exposed, ie, 
blowing highlights. Not good, especially since the highlights are 
more important than the shadows in the majority of photos as they 
attract the eyes. A light meter does not indicate the correct 
exposure, it just lets you know the light values and corresponding 
exposure if the scene were of an averaged 18% grey. You then apply 
your experience to modify that to determine the correct exposure.

With my Canons I avoid blowing highlights by setting exposure to -1/3 
for average shots; with the M8 I set it to -2/3 for average shots. If 
there are any large dark, very light or other anomalous areas, I 
adjust as required. Critical stuff gets a trial shot, histogram 
analysis and manual exposure.

Over-exposing means not exposing correctly, as does underexposing.

If you clip some bits in the highlights, you better be sure they're 
the sun, some other light source or specular reflections, and even 
then the adjacent transition areas are susceptible to non-correctable 
colour shifts. It's the nature of clipped digital information. 
Distortion. And that's what you avoid by staying away from clipped 
highlights.


-- 

    *            Henning J. Wulff
   /|\      Wulff Photography & Design
  /###\   mailto:henningw@archiphoto.com
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