Photography glossary

All 122 words from the course, each explained in one sentence, from acutance to zoom. In the lessons they're highlighted in color: tap them to read the definition.

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1

180-degree rule: In video, using a shutter speed of double the frame rate, for example 1/60 at 30 fps or 1/50 at 25 fps.

5

500 rule: A guide for photographing stars: 500 divided by the equivalent focal length gives the maximum exposure in seconds before trails appear.

A

A mode: Aperture priority: you choose the aperture and the camera chooses the shutter speed. Canon calls it Av.
Acutance: Contrast at the edges in an image. The higher it is, the sharper the photo looks.
AF-C: Continuous autofocus: it keeps focusing on the subject while it moves.
AF-S: Autofocus that focuses once and locks. For still subjects.
Aperture: The size of the opening in the diaphragm that lets light in. It's given as an f-number.
APS-C: A sensor size common in mid-range cameras, with a crop factor of 1.5.
Auto ISO: A mode where the camera adjusts the ISO to the light, within a limit and respecting the minimum shutter speed you set.
Autofocus: A system that focuses automatically. Abbreviated AF.

B

Back-button focus: A setup that assigns focusing to a button on the back of the camera (AF-ON) and leaves the shutter button just for taking the picture.
Backlight: Light coming from behind the subject.
Blue hour: The time just after sunset, when the sky is a deep blue.
Bokeh: The look of the out-of-focus background, especially points of light, which turn into circles.
Burst mode: A drive mode that takes photos continuously while you hold down the shutter button.

C

Camera shake: A whole image blurred by the camera moving when shooting handheld at too slow a shutter speed.
Catchlight: A small reflection of light in the eyes that brings them to life.
Center-weighted metering: A metering mode that takes the whole frame into account but gives more weight to the center.
Circle of confusion: The largest size a blurred point can be and still look sharp to the eye. It's the basis for calculating depth of field.
Clipped highlights: Areas of the image that have turned pure white, with no information. On the histogram, the graph is pushed against the right edge.
Color space: The range of colors an image can represent. sRGB is the standard for screens and the web; Adobe RGB, which is wider, is used for printing.
Contrast: The difference between the light and dark areas.
Crop factor: A multiplier that shows how a focal length behaves on a sensor smaller than full frame.

D

Decisive moment: The instant when all the elements of a scene fall into place. An idea popularized by Henri Cartier-Bresson.
Depth of field: The area of the image, in front of and behind the focus point, that looks sharp. It depends on the aperture, distance, focal length and sensor size.
Detail shot: A very tight frame on one specific element.
Diaphragm: A mechanism of blades inside the lens that opens or closes to let light through.
Diffraction: A loss of sharpness that appears when you stop the aperture down a lot, usually from f/16.
Digital zoom: An enlarged crop of the image. It loses quality.
Dragging the shutter: A technique that combines flash with a slow shutter speed so the ambient light in the background shows.
DSLR: A camera that uses a mirror to send the image to an optical viewfinder.
Dynamic range: The difference between the lightest and darkest areas a sensor can record while keeping detail.

E

Environmental portrait: A portrait that shows the person in their surroundings, which tell as much as they do.
Expose to the right: A technique (ETTR) of giving the most exposure possible without blowing the highlights and then darkening in editing, to get less noise.
Exposure: The amount of light the sensor receives during the shot. It's set by the aperture, shutter speed and ISO.
Exposure compensation: A setting that brightens (+) or darkens (−) the exposure the camera calculates in P, A and S modes.
Exposure lock: A feature (AE-L) that holds the metered exposure so you can reframe without it changing.
Exposure value: A number (EV) that sums up a combination of aperture and shutter speed. Combinations with the same EV give the same brightness.
Eye detection: An autofocus feature that recognizes the eyes of people or animals and focuses on them automatically.

F

F-number: The ratio between the focal length and the diameter of the aperture. The smaller it is, the wider open the diaphragm and the more light gets in.
Fast lens: A very bright lens, with a large maximum aperture (f/1.4, f/1.8, f/2.8), that lets you use faster shutter speeds.
Fill flash: Low-power flash that lifts the shadows without overpowering the natural light.
Fisheye: A lens with a very short focal length, a field of view of up to 180 degrees and strong curved distortion.
Flash sync speed: The fastest shutter speed at which the camera can use flash, usually 1/200 or 1/250.
Focal length: A distance in millimeters that tells you how much a lens takes in.
Focus area: The part of the frame the camera uses to focus: a single point, a zone or the whole frame.
Focus peaking: A manual focus aid that highlights in-focus edges in color.
Focus stacking: Combining several photos focused at different distances to extend the sharp area.
Frames per second: The number of images that make up each second of video. Abbreviated fps.
Framing: What you decide goes into the photo and how you arrange it.
Full frame: A sensor the size of the old 35 mm negative, 36 × 24 mm. It's the reference for calculating equivalent focal lengths.

G

Golden hour: The time just after sunrise and before sunset, with low, warm, soft light.
Golden ratio: A ratio of 1 to 1.618 used in composition to place the main elements. It gives rise to the golden grid and golden spiral.
Golden triangle: A composition device that divides the frame into four triangles with a diagonal and two lines perpendicular to it.
Gray card: A neutral gray card you photograph to meter exposure or set an exact white balance.

H

Hard light: Light from a small or distant source. It creates strong shadows with sharp edges.
HDR: A technique that combines several photos to keep detail in both highlights and shadows.
Highlight warning: A feature that makes the blown-out areas of the photo blink on the screen. In video it's called zebras.
Histogram: A graph showing the distribution of tones in the image, from blacks (left) to whites (right).
HSS: High-speed sync: lets you use flash above the flash sync speed.
Hyperfocal distance: The focus distance that gives the largest possible sharp area: from half that distance to infinity.

I

Image stabilization: A system in the camera or lens that compensates for hand shake and allows slower handheld shutter speeds.
Inverse square law: The principle that, when you double the distance to a light source, the subject receives a quarter of the light.
ISO: A setting that amplifies the sensor's signal. Raising it brightens the image, but also amplifies the noise.

J

JPEG: An image format that's already processed and compressed, ready to share.

K

Kelvin: The unit (K) used to measure the color temperature of light.

L

Leading lines: Lines in the scene that lead the eye toward the subject.
Lens: The set of glass elements that forms the image on the sensor.
Lens hood: A piece that attaches to the front of the lens to stop side light from causing flare and loss of contrast.
Lens speed: A lens's maximum aperture. The lower its f-number, the faster it is and the more light it lets in.
Light meter: The camera system that measures light and calculates exposure assuming the scene is, on average, a mid gray.
Light pollution: The artificial glow from cities that lights up the night sky and hides the stars.
Long exposure: A photo with the shutter open for one or more seconds. It needs a tripod.

M

M mode: Manual mode: you choose aperture, shutter speed and ISO.
Macro: Photography at very close range that reproduces the object at life size or larger on the sensor.
Magnification ratio: The ratio between the size of the object on the sensor and its real size. In true macro it's 1:1.
Matrix metering: A metering mode that splits the frame into zones and analyzes them separately. Canon calls it evaluative; Sony and Fujifilm, multi-segment or multi.
Medium format: A sensor format larger than full frame; in the most common digital cameras it measures about 44 × 33 mm.
Medium shot: A frame that shows the subject recognizably, without all of its surroundings.
Megapixel: One million pixels. It tells you the sensor's resolution, but doesn't determine image quality on its own.
Micro Four Thirds: A sensor format of about 17.3 × 13 mm, with a crop factor of 2, used by OM System (formerly Olympus) and Panasonic.
Minimum focus distance: The shortest distance at which a lens can focus.
Mirrorless: An interchangeable-lens camera with an electronic viewfinder instead of a mirror.

N

ND filter: Neutral density filter: it reduces the light coming in without changing the colors.
Negative space: The empty area around the subject that gives it prominence.
Noise: Grain and color specks that appear at high ISO or in low light, especially in the shadows.

O

Overexposed: A photo with too much light: the bright areas come out white and lose detail.

P

Panning: Following a moving subject with the camera during a slow exposure: the subject stays sharp and the background turns into streaks.
Photo series: A set of photos meant to be seen together to tell a story.
Polarizer: A filter that darkens the sky, removes reflections and saturates colors.
Portrait mode: A phone feature that blurs the background with software.
Prime lens: A lens with a single focal length. It's usually faster and sharper than a zoom.

R

RAW: A file with all the unprocessed data from the sensor. It gives you more latitude when editing.
Reflector: A white, silver or gold surface that bounces light to fill in shadows.
Resolution: The amount of fine detail the lens and sensor can record. In a digital image it's expressed in pixels.
Rule of odds: A composition guideline that says groups of three or five elements are more appealing than even numbers.
Rule of thirds: Dividing the image into nine equal parts and placing what matters on the lines or where they cross.

S

S mode: Shutter priority: you choose the shutter speed and the camera chooses the aperture. Canon calls it Tv.
S-curve: An S-shaped curved line, like a river or a path, that leads the eye through the image.
Saturation: The intensity of the colors.
Sensor: The chip that turns light into a digital image. Its size affects noise, dynamic range and background blur.
Shutter: A curtain that opens to let light in for the length of the exposure.
Shutter speed: How long the shutter lets light reach the sensor, for example 1/250 of a second.
Slow motion: Video recorded at more frames per second than it's played back at.
Soft light: Light from a large or diffused source. It creates light, gradual shadows.
Spot metering: A metering mode that only analyzes a small circle of the frame, between 1 and 5%.
Stop: The unit for measuring light in photography: each stop doubles or halves the amount of light.
Sweet spot: The aperture at which a lens is sharpest, usually between f/8 and f/11.

T

Telephoto: A long focal length lens that brings distant things closer.
Temperature: A setting that makes the photo warmer (orange) or cooler (blue).
Third of a stop: The increment in which most cameras adjust aperture, shutter speed and ISO. Three thirds make a full stop.
Tint: The second white balance setting, which corrects green or magenta color casts.
Tripod: A three-legged stand that holds the camera still.

U

Underexposed: A photo with too little light: it comes out dark and loses detail in the shadows.

V

Viewfinder: The window you look through to frame the shot.
Vignette: Darkening of the corners of the photo.
Vignetting: The natural darkening of the image corners, most visible at a lens's maximum aperture.
Visual weight: An element's ability to attract the eye. Size, brightness, saturation, contrast or the presence of faces increase it.

W

White balance: A setting that compensates for the color of the light so whites look neutral.
Wide shot: A wide frame that sets the scene.
Wide-angle: A short focal length lens that takes in a wide field of view.

Z

Zone focusing: Fixing the focus at a set distance and stopping down so everything that passes through that zone comes out sharp.