- 500 rule
- 500 divided by the full-frame-equivalent focal length gives the longest exposure before stars trail. Learn more
- Aperture
- The adjustable opening in a lens that controls how much light passes through. Written as an f-number. Learn more
- Aperture priority (A/Av)
- A mode where you set the aperture and the camera chooses the shutter speed. Learn more
- APS-C
- A sensor smaller than full frame, with a crop factor of about 1.5 (1.6 on Canon). Used in many mid-range cameras.
- Auto ISO
- A setting that lets the camera choose ISO while you choose aperture and shutter speed. Learn more
- Bokeh
- The look of out-of-focus areas, especially points of light that turn into discs. Learn more
- Bulb mode
- A shutter setting that keeps the shutter open as long as the button is held, for exposures over 30 seconds. Learn more
- Camera shake
- Blur across the whole frame caused by the camera moving during the exposure. Learn more
- Circle of confusion
- The largest blur spot that still looks sharp. Used to calculate depth of field; 0.03 mm on full frame. Learn more
- Crop factor
- How much smaller a sensor is than full frame. Multiply focal length by it to get the full-frame equivalent field of view.
- Depth of field
- The range of distances in a photo that look acceptably sharp. Learn more
- Diffraction
- Softening of the whole image at very small apertures, usually noticeable past f/11 to f/16. Learn more
- Dynamic range
- The span from the darkest to the brightest tones a sensor can record with detail, measured in stops.
- Exposure
- The total amount of light that reaches the sensor, set by aperture, shutter speed and ISO. Learn more
- Exposure compensation
- A control that tells the camera to make a photo brighter or darker than its meter suggests, in thirds of a stop. Learn more
- Exposure triangle
- The relationship between aperture, shutter speed and ISO. Learn more
- Exposure value (EV)
- A single number for a combination of aperture and shutter speed, or for the brightness of a scene. Learn more
- F-number (f-stop)
- Focal length divided by the diameter of the aperture. Smaller numbers mean bigger openings. Learn more
- Focal length
- The lens’s angle of view in millimeters. Short focal lengths are wide, long ones magnify.
- Full frame
- A 36 × 24 mm sensor, the same size as a 35mm film frame.
- Highlight clipping
- Bright areas recorded as pure white with no detail. Also called blown highlights. Learn more
- Histogram
- A graph of how many pixels are at each brightness level, from black on the left to white on the right. Learn more
- Hyperfocal distance
- The focus distance that keeps everything from half that distance to infinity sharp. Learn more
- Image stabilization
- A lens or sensor mechanism that counteracts hand movement, allowing slower handheld shutter speeds. Learn more
- ISO
- How much the camera amplifies the signal from the sensor. Higher ISO is brighter and noisier. Learn more
- Light meter
- The camera’s measurement of scene brightness, shown as a scale with 0 for a balanced exposure. Learn more
- Manual mode (M)
- A shooting mode where you set aperture, shutter speed and ISO yourself. Learn more
- Motion blur
- Blur of moving subjects caused by a shutter speed too slow to freeze them. Learn more
- ND filter
- Neutral density filter: dark glass that reduces light evenly to allow slower shutter speeds. Learn more
- Noise
- Random grain and color speckles in an image, made stronger by high ISO and underexposure. Learn more
- NPF rule
- A formula for the longest exposure before stars trail, accounting for aperture, pixel size and focal length. Learn more
- Shutter priority (S/Tv)
- A mode where you set the shutter speed and the camera chooses the aperture. Learn more
- Shutter speed
- How long the shutter stays open, from 1/8000 s to 30 s or longer. Learn more
- Stop
- A doubling or halving of light. The common unit for aperture, shutter speed and ISO. Learn more
- Sunny 16 rule
- In bright sun, use f/16 and a shutter speed of 1 over your ISO. Learn more