What Are the Numbers on a Camera Lens?

What Are the Numbers on a Camera Lens?
Camera lenses are the most important part of any camera. The quality of the optics greatly affects picture quality. When looking at a camera lens, you will see a series of numbers that give you information about the lens.

SLR Lens Focal Length

Focal length is a more accurate way of looking at zoom in a telephoto lens, or how much magnification there is in a prime lens on an SLR. Common focal lengths are 18-55, 24-70, 50mm, 60mm, 70-200 and 70-300. These numbers will be printed on the lens by the glass.

Adjusting Focal Length

Rotating the lens barrel adjusts focal length on an SLR zoom lens; these numbers are printed on the lens barrel. For instance, a 24-70 will often list 24, 35, 50 and 70 on the barrel of the lens.


Aperture numbers, expressed as an F number, are also shown.

Variable Aperture numbers

If you see two F numbers, it is a variable aperture lens such as the Nikon 18-200 lens, which is an F3.5-5.6.

Point and Shoot

Point-and-shoot lenses will display the aperture for the lens, which is always variable. They will also usually list the optical zoom (3x, 4x) and focal length.

Article Written By Candace Horgan

Candace Horgan has worked as a freelance journalist for more than 12 years. Her work has appeared in various print and online publications, including the "Denver Post" and "Mix." Horgan holds a Bachelor of Arts in English and history.

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