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Changing the lens aperture to a smaller opening.  For example, from f/8 to f/11.

Stopping down

A lens that makes a subject appear larger than does a normal lens at the same camera to subject distance.  A telephoto lens has a longer focal length and narrower field of view than a normal lens and have a shallower depth of field than wide angle lenses.  

Telephoto lens

Through the lens


Viewing a scene to be photographed through the same lens that admits light.

TTL focusing

In a single lens-reflex (SLR) camera the view seen through the viewfinder is that seen through the lens.  

TTL viewing

The light meter built into the camera determines exposure for the scene by reading light that passes through the lens during picture-taking.  SLR cameras have built in meters which measure light after it has passed through the lens, a feature that enables exposure readings to be taken from the actual image about to be recorded, whatever the lens angle of view and regardless of whether a filter is used or not.

TTL Metering

The degree of lightness or darkness in any given area of a photo.  Cold tones (bluish) and warm tones (reddish) refer to the colour of the image in both black and white and colour photographs.


A three-legged supporting stand used to hold the camera steady.  Especially useful when using slow shutter speeds and/or telephoto lenses.


Underexposure of image corners produced deliberately by shading or unintentionally by inappropriate equipment, such as unsuitable lens hood or badly designed lens.  A common fault of wide angle lenses, owing to reflection cut-off of some of the very oblique rays.  May be caused in some long-focus lenses by the length of the lens barrel.


A lens that has a shorter focal length and a wider field of view (includes more subject area) than a normal lens.  

Wide angle lens