Archived posting to the Leica Users Group, 2006/09/20

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Subject: [Leica] Re: the dynamic range of digital
From: abridge at (Adam Bridge)
Date: Wed Sep 20 09:44:49 2006
References: <> <BAY116-F96940FBB99F5FB60199C89F230@phx.gbl>

Mark Davison has the best explaination - it's an interaction between
the camera's built-in metering and the after-the-fact metering that
the histogram (hopefully the RGB histogram) gives you.

Ultimately it's the captured image that informs how you shoot, right?

So there are two systems working FOR you on a digital camera:

BEFORE the shot you have the camera's built-in exposure metering
system. It can be simple or quite advanced - but however it works it's
a best-estimate approximation of what the camera vendor THINKS,
SUSPECTS, IMAGINES will be what you want.

AFTER the shot you have the histogram produced by the camera that
shows you a representation of the image as recorded by the sensor.
It's what's REALLY THERE and, ultimately it can be the final arbiter
of exposure if you have time to use it. On my camera over-exposed
areas show up flashing. I don't know how the DMR or M8 show these
blown highlights. But the histogram is the key and using the data
there we're free to adjust the exposure so what is captured exploits
the dynamic range the camera is capable of recording.

Doug has learned what he needs to adjust so for him the camera's
metering more closely approximates what is captured. B D has his own
system for doing same and I have another since I'm using a different
camera body. Henning will probably have a different adjustment for the
M8 and Ted today will be out there snapping in full auto mode and
still making great images.

Ain't technology wonderful?

And Mark, thanks for the post, I learned something and you clarified
something in my mind that hadn't quite jelled after a year!


In reply to: Message from bd at (B. D. Colen) ([Leica] Re: the dynamic range of digital)
Message from davison_m at (MARK DAVISON) ([Leica] Re: the dynamic range of digital)