Focal Length

MMs

Lenses have focal length measured in millimeters (mm).

A 500mm lens has only one focal length.

It has a fixed focal length of 500mm.

A zoom lens, such as a 18mm to 200mm, has all of the focal lengths between those two focal lengths.

Wide-angle

Focal Lengths

A focal length less than 75mm with most digital SLR cameras is wide angle.

The lens can "see" more of a scene from left to right.

Telephoto

Focal Lengths

If a focal length is greater than 75mm, the lens is telephoto.

The lens is like a telescope.

Examples

In the photographs below, the camera was not moved.

Note how the yellow bush and orange flower are in the center of each photograph.

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18mm (28mm)*

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50mm (75mm)

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70mm (105mm)

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450mm (300mm)

* The second figure is for film cameras.

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Focal Length