Project Educate: Photography ABCs [Part One]

A

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Aperture

The aperture is the opening that allows light to enter your camera - it's usually a circular part of the lens. The size of the aperture is described in f-stops, written as numbers like f/1.8 and f/8, where a larger number on the bottom means the light entering your camera is being divided by a larger denominator.

Most lenses allow you to open or close your aperture to change the exposure: by opening your aperture (moving from a smaller aperture to a larger one - from a larger f-number like f/22 to a smaller one like f/11) you let more light into the camera and the image is more exposed. Older lenses and manual cameras will usually have a ring on the lens to change the aperture, but newer cameras generally have an aperture setting in the camera itself that changes it automatically when the shutter release is pressed.

Opening your aperture also makes your depth of field - the range of focus that is sharp - narrower, and closing your aperture makes it wider.

B

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Back Lighting

Back lighting is a technique used in a wide variety of photography for two very different reasons. Many of you have probably had a passport photo taken, and when the camera's flash went off it triggered another, off-camera flash that lit up the background behind you - this type of back lighting is a type of fill flash, used to eliminate shadows behind the subject.

It's also used, though, for artistic effect in silhouette photographs. By making the background of the image much brighter than the foreground, you can meter the photo's background as being of average brightness and thereby make the subject look darker or even completely shadowed. By exposing it so that the image is metered normally on the subject instead of the background, you can create a look of light wrapping around the subject.

C

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Colour Balance

Colour balance is a term used in colour photography meaning that, under a given light source, the medium you're using to take the picture would reproduce a full range of grey tones accurately. It basically means the same thing as white balance.

Most digital cameras can adjust for this using automatic or manual white balance settings, but different colour films have widely different balances and are better for specific uses if accurate representation of colour is desired - Fujichrome Velvia films are balanced to truthfully capture images shot in sunlight and are often used in nature photography, whereas Fujicolor Pro NPL 160 was balanced for exposure under tungsten lighting and was a good everyday indoor photography film.

Use of "improper" colour balance can be used for artistic effect, to give your images a cooler or warmer palette.

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Double Exposure

Double exposure is one of the more common "alternative" photography techniques - it is the capture of two different images on one frame, so that they blend together as sort of an overlay.

It's relatively common in film photography, being done intentionally but also happening sometimes by accident if your camera doesn't automatically wind after you take a picture and you forget to advance the frame, but is a bit more rare with digital photography, where it is an example of digital darkroom technique (post-production of digital work to make it approximate what is possible with film photography).