Camera Operation
Camera Operation tests whether you can actually run a camera: set exposure, balance colour, focus, and move the camera for a reason. Questions come as practical scenarios, so answer with a decision and the setting that achieves it.
Lens, exposure and focus
- Focal length sets angle of view: short (wide) exaggerates depth, long (telephoto) compresses it.
- f-number N = focal length / entrance pupil diameter, so f/2 on a 50 mm lens means a 25 mm pupil.
- One stop halves or doubles light: f/1.4, 2, 2.8, 4, 5.6, 8, 11, 16.
- Depth of field grows with a smaller aperture (higher f-number), shorter focal length and greater subject distance; it shrinks when you move closer or zoom in.
- Exposure triangle: aperture, shutter speed (or angle) and gain/ISO. Use ND filters rather than stopping down too far or raising gain in bright light.
- White balance matches the camera to the illuminant colour temperature: tungsten about 3200 K, daylight about 5600 K, overcast 6500 to 7000 K. Set the higher Kelvin value under warmer light to neutralise it.
Camera craft
- Movements: pan (horizontal pivot), tilt (vertical pivot), dolly/track (move whole camera), zoom (change focal length), pedestal (raise or lower), arc.
- Zoom changes framing without changing perspective; dolly changes perspective by changing viewpoint.
- Back focus must be set so the lens holds focus through the zoom range.
- Support, cable safety, battery rotation and media offload are part of operating.
Worked example. A 50 mm lens at f/2 has a 25 mm pupil; closing to f/4 quarters the light, that is two stops, and deepens the depth of field, which suits a two-person interview.
Traps
- Reading a large f-number as a large aperture; f/16 is tiny.
- Using gain to fix underexposure and accepting the noise.
- Calling a zoom a dolly shot when the perspective never changes.
- Leaving auto white balance on during a mixed tungsten-daylight scene.