Correct Exposure is The Exposure You Want
The Camera Light Meter
Is a sophisticated but mindless tool
Sometimes right, sometimes wrong
But even when right,
It can’t read your mind
Yearning for Spring
The exposure I wanted ;-), a 10-shot multiple exposure
Dogwoods & Redbuds – Shenandoah NP April 2011
Already a few cherry blossoms – in mid-February 2012???
Today’s cameras contain excellent light meters – some better than others but all excellent.
1. Your camera’s light meter measures light (duh) and
2. Based on the measurement, it recommends exposure setting alternatives –
Which depend on –
The exposure mode you’ve selected (manual, aperture priority, automatic, etc.)
The metering option you’ve selected (matrix, centered, spot, etc.)
The settings provided are f/stop & shutter speed combinations any of which will give a theoretically correct exposure
f/16 @ 1/100 sec, or f/11 @ 1/200, or….
In the simplest terms that’s all that it does –
provide aperture and shutter settings for a “theoretically correct” exposure (TCE) –
TCE = exposure settings that result in an overall image tonality of middle gray
What is a correct exposure? (not “theoretically correct”)
It’s the exposure that you want –
and the light meter can’t read your mind!
It’s designed to do just one thing, provide the TCE
but – you may not want TCE even if it’s right
or – the TCE may be wrong, fooled by the conditions
You may want a high or low key image.
The meter doesn’t know how to do this without your intervention.
You will have to compensate by adjusting exposure compensation for example.
Or, you may want white snow.
The meter wants the tonality of the overall scene to average out to middle gray – and is fooled.
You may have to increase the exposure compensation to compensate and make your gray snow white.
Or, you may want detail in a blackbird silhouetted against a bright sky
Depending on your meter mode selection the bird may be far from black (and without detail)
Such as when your mode selection includes the sky
You’d better spot meter on that blackbird
Enlarge for detail
Without spot metering, a black silhouette
And on & on….
such as a scene’s tonal range exceeds the sensor’s capability –
either expose for the dark or for the bright and accept the consequences, or
shoot several exposures for HDR, or
try a grad neutral density filter
Bottom line, the light meter is a sophisticated one-trick pony.
Often that trick isn’t the one you want or need
You have to know how to compensate, usually by some combination of
1. Adjusting exposure compensation and|or
2. Selecting the most appropriate metering mode
The dedicated photographer will learn to do these things –
instinctively & automatically
practice, practice, practice.
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