Photography glossary

Film photography has its own vocabulary. These 26 terms cover everything you'll meet in the docs. Each entry explains the idea in plain language and links to the features in the app that use it.

A

Aperture

The opening inside the lens that controls how much light passes through.

Also called: f-stop, f-number

B

Bellows extension

Light loss that happens when you focus close on a view camera with extending bellows.

Bracketing

Shooting the same scene at multiple exposures to hedge your bet.

Also called: exposure bracket

Bulb mode

A shutter mode that keeps the shutter open for as long as you hold the release.

Also called: B mode, bulb

C

Calibration

Adjusting your meter so its readings match a known reference.

Color temperature

How warm or cool a light source looks, measured in Kelvin.

Also called: Kelvin, white balance

D

Depth of field

The range of distances in your scene that look acceptably sharp.

Also called: DoF

E

Exposure value

A single number that describes how much light a scene has.

Also called: EV

F

False color

An overlay that paints each part of the image a color based on how bright it is.

Film latitude

How forgiving a film stock is to exposure errors.

Also called: dynamic range of film

Filter factor

How many stops of light a colored, ND, or polarizing filter absorbs.

G

Guide Number

A flash's power rating, expressed as a distance times an f-stop.

Also called: GN

H

Histogram

A graph that shows how many pixels there are at each brightness level.

Hyperfocal distance

The closest focus distance that keeps infinity acceptably sharp at a given aperture.

I

Incident light

Light that is falling onto your subject, as opposed to bouncing off it.

ISO

How sensitive your film or sensor is to light.

Also called: film speed, ASA

M

Multi-spot metering

Taking spot readings at several points in the scene and combining them.

P

Pulldown

The process of converting 24 fps film to 30 fps video.

Also called: 3:2 pulldown

Push and pull processing

Developing film longer or shorter than rated, to change effective ISO.

Also called: push processing, pull processing

R

Reciprocity failure

Film loses sensitivity at very long exposures, so the meter reading is no longer enough.

Also called: reciprocity, reciprocity law failure

Reflected light

Light that has bounced off your subject and traveled back to the meter or camera.

S

Shutter speed

How long the shutter stays open to let light hit the film or sensor.

Spot metering

A reading taken from a small, precisely-targeted area in the scene.

Also called: spot meter

Stop

A doubling or halving of light. The unit of exposure.

Sunny 16 rule

On a sunny day, set your aperture to f/16 and shutter to the reciprocal of your ISO.

Also called: Sunny 16

Z

Zone system

A way of placing tones on a 0 through 10 scale, devised by Ansel Adams.

Also called: zones