| aberration |
A defect in a lens which results in images
that are slightly damaged or out of focus. |
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| AE |
Short for 'automatic exposure'. On Canon cameras,
this is the Av mode (where the photographer selects the aperture
and the camera then selects the shutter speed). |
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| AF |
Short for 'automatic focus'. Automatic focus comes
with most lenses; some have predictive auto-focus even, which means
they'll try to predict focus for targets that move towards or away
from the camera. |
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| aperture |
The opening that lets through light onto the CCD/CMOS
chip. The diaphragm allows to vary the aperture (by opening and closing
more or less). The aperture is shown as a ratio such as f/2.8, f/8
etc. Note that each stop means twice as much (or half as much) light
falling onto the 'film'. |
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| Av |
Short for 'aperture value'. This is a mode on Canon
cameras where you select the aperture, and
exposure time is selected by the camera. |
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| bokeh |
Blur of the background of a photograph; anything
that is not in focus really. Bokeh is used
to separate the (focused) subject from its surroundings (often used
in portrait photography). You can achieve bokeh by using a large aperture
and/or using a long lens (for example a 100mm f/2). |
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| bounce flash |
Using a flash unit which can be directed to the ceiling
(or nearby wall) to create indirect lighting of a subject. This creates
more subtle lighting and shadows, provided the ceiling (or wall) isn't
too far away (in which case the lighting may be too dark). Check
the flashing page for an example. |
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| fast lens |
A lens which lets much light pass to the sensor.
This allows you to select shorter shutter times, or higher ISO values,
or lower aperture sizes. Faster lenses are generally more expensive
though. Examples are 50mm f/1.4. |
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| fixed focal
length |
Characteristic of a lens which cannot zoom; this
means you'll have to move around to frame your subject (instead of
using zoom) or you have to crop later (which costs resolution).
Disadvantages: the need to move around
Advantages:
mostly these lenses are 'faster',
meaning they need less light to still give a good image. |
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| purple fringing |
This effect appears on many lenses; in highly contrasting
areas, you get (if shown at 100% view) purple-colored edges. |
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