What the heck is ETTR and ETTL?

Photography is all about the exposure – but is there a special strategy to achieving exposure? Check out this article which covers a few strategies and their advantage and disadvantages:



Strategy: Aim to expose the image so that its histogram shifts as far to the right as possible without clipping the highlights, even if this results in over-exposure. A negative exposure compensation is later applied (during RAW development) to get the image back to a standard exposure.


Maximizes the number of tones recorded.

Note: many recent digital SLR cameras have RAW files which record tones with 14-bit precision, so this is less of a factor than it used to be. It is highly unlikely that a RAW image will have insufficient tones (and become posterized) as long as it isn’t grossly underexposed.
See the tutorial on image posterization for more on this topic.

Minimizes image noise because lighter (and therefore less noisy) tones get darkened after exposure compensation is applied. The total reduction in noise will depend on how much the photo is able to be over-exposed without clipping.


Has a high risk of clipping the highlights, especially in the individual color channels (which can lead to unrealistic color shifts).

Requires more light than normal, and potentially a higher ISO speed
(which could mitigate any reduction in image noise from ETTR).

Makes judging/pruning photos more difficult since subjects will likely appear over-exposed (until exposure compensation is applied in post-processing).

May require several shots (followed by histogram inspection) in order to position the histogram as intended. One also needs to look at the color histogram in order to avoid clipping in any of the individual color channels.

Cambridge in Colour | Read the Full Article

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