Reference · Glossary
Exposure Terms in Plain Words
Camera manuals can read like another language. Here are the words you will meet in our guides and in the field, explained the way a friend would explain them in a hide.
A
- Aperture
- The adjustable opening in the lens, written as an f-number. A small number such as f/4 is a wide opening that lets in more light and blurs the background.
- Auto-ISO
- The camera picks the ISO for you while you fix shutter speed and aperture. Ideal for wildlife, where light changes as animals move.
- Autofocus tracking
- A focus mode that follows a moving subject across the frame. Often called continuous AF, AI Servo or AF-C.
B
- Back-button focus
- Moving autofocus from the shutter button to a button on the back, so you can hold focus on a perched bird and shoot the instant it moves.
- Backlight
- Light coming from behind the subject, which creates a glowing rim around fur and feathers.
- Bokeh
- The quality of the out-of-focus areas. Smooth bokeh makes a wild subject stand out from a busy hedge.
C
- Catchlight
- The small reflection of light in an animal's eye. It brings a portrait to life and is easiest to catch when the sun is low.
- Crop factor
- How much a smaller sensor narrows the field of view compared with full frame. A 1.5× crop makes a 400 mm lens frame like 600 mm.
D
- Depth of field
- How much of the scene, front to back, looks sharp. Wide apertures, long lenses and close subjects all make it shallower.
- Dynamic range
- The span from darkest to brightest detail a sensor can record. White birds on dark water test it hard.
E
- Exposure
- How much light reaches the sensor, set by shutter speed, aperture and ISO together.
- Exposure compensation
- Telling the camera to make the picture brighter or darker than its meter suggests, measured in stops (EV).
F
- f-stop
- Another name for the aperture setting. Each full stop, such as f/5.6 to f/8, halves the light.
- Focal length
- The lens's magnification, in millimetres. Longer focal lengths make distant animals larger in the frame.
G
- Golden hour
- Roughly the first and last hour of direct sunlight, when light is warm, soft and low.
H
- Highlight clipping
- When the brightest areas turn pure white with no detail. Many cameras show it as flashing "blinkies" on playback.
- Histogram
- A graph of the tones in your image. If it piles up against the right edge, highlights are being lost.
I
- ISO
- The sensor's brightness amplification. Higher ISO lets you keep a fast shutter in poor light, at the cost of more noise.
- Image stabilisation
- Lens or sensor technology that reduces blur from your own shake. It does not stop the animal's movement.
M
- Metering
- How the camera measures light. Spot or centre-weighted metering helps when a small subject sits against a bright sky.
N
- Noise
- Grainy speckles, most visible in shadows at high ISO. Modern software reduces it well; a blurred subject cannot be fixed.
P
- Panning
- Following a moving animal with a slow shutter so it stays fairly sharp while the background streaks into motion.
- Pre-capture
- A mode on some cameras that records frames just before you fully press the shutter, useful for take-offs.
R
- RAW
- A file holding all the sensor's data, giving far more room to recover highlights and shadows than a JPEG.
S
- Shutter speed
- How long the sensor is exposed, such as 1/1000 s. Faster speeds freeze movement.
- Silent shutter
- An electronic shutter that makes no sound; helpful near nervous animals, though fast motion can distort.
- Stop
- A doubling or halving of light, whether by shutter, aperture or ISO.
W
- White balance
- How the camera interprets the colour of light. Auto works well; shooting RAW lets you adjust it freely later.