The aperture is the term used to describe the size of the hole in the front of the camera that permits light to enter and fall on the film (or the electronic image sensor) that is collecting the light. The device that controls the size of the aperture is known as the iris. Hence the setting that measures the iris 'hole' size is known as the aperture.

Aperture is measured in f-stops and these range from f1.4 (fully open) through f2.0, f2.8, f4, f5., f8, f11 and f16, right up to f22 (fully closed). I.e. the larger the f-stop number the smaller the aperture size-the smaller the size of the hole permitting light into the camera. f1 .4 permits twice as much light as f2.0 and f2 .0 permits twice as much lighting as f2 .8.

Sample Scrims

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A selection of metal lighting scrims (note the half and graduated scrims that reduce the beam of light by the level of fineness in the meshing) Image ©Cirrolite

Many Film and TV productions often use constant lighting in the studio and on location, and because some types of bulbs cannot be electrically dimmed because of their design, scrims are used to reduce the intensity of the light. This is because tungsten / incandescent bulbs will progressively change in colour temperature, becoming more orange, as they are dimmed. Scrims are therefore regarded as a “colour safe” alternative to electrically dimming lights, and are a fine wire mesh available in different strengths, placed directly in front of the light. A half scrim, as the name suggests, has only has the mesh half way across, which will allow the full intensity of light to fall on part of a scene. A graduated scrim varies the intensity of light from across it.

The concept of the drawing power of the lens is a lesser-known and somewhat specialist term used in photography and cinematography.

At its simplest, the drawing power of the lens relates to how rapidly an object's furthest components fall away to the vanishing point of a shot, compared to those nearest. It relates to how angler the perspective of a shot it. If you think about a shot featuring a skyscraper, a lens with high drawing power would show quickly tapering tops of the sky scrapers, as the higher floors are further away. Thus typically wider angle lenses (those with a shorter focal length) have a greater drawing power than normal focal length or long (telephoto) lenses.