Metering for negative film

Why shadows

Negative film holds highlight detail far better than it holds shadow detail. Once a shadow records nothing, there is nothing to recover; a highlight that is dense still carries information you can print through.

In practice

Meter the darkest area where you want visible detail and place it two or three stops below your meter's mid-tone reading. With an in-camera averaging meter, that usually means giving between half a stop and a full stop more exposure than it suggests.

Latitude is not an excuse

Colour negative film tolerates overexposure remarkably well and underexposure badly. That asymmetry is why "expose for the shadows" is advice rather than superstition — the failure modes are not symmetrical.

Slide film is the opposite

Reversal film has almost no highlight latitude. There you meter for the brightest area you want to hold, and let the shadows fall where they fall.