More photography terms explained, courtesy of The Glossary of Digital Photography by John G. Blair (Rocky Nook, 2008, $40):

Evaluative Metering An automatic metering system developed by Canon. The scene is divided into a number of zones. The exposure is calculated for each zone separately. Then a complex calculation is made of all of the individual zone exposures to create the best possible exposure automatically.

Optical Resolution Refers to the native resolution of a scanner before any electronic or digital interpolation of the image. The higher the optical resolution, the finer the detail resolved by the scanner.

Effective Resolution 1) A way to measure and compare a film original to a digital original. 2) Scaling an image in a page-layout program. Unless data is added when the image is scaled up , or thrown away when the image is scaled down, the same number of pixels will exist in the larger or smaller image. The resolution of the image has to change proportionally to make up for this phenomenon. This new resolution is know as the effective resolution.

(click here for our previous “In Terms of Photography”)