what do the numbers on a camera lens (75-300, 28-55...) mean?

Question

Hi, i was wondering what can i learn about the lens from the numbers written on it. (I know what the numbers with the "f" is for)

Answer 1

The lens "mm" marking tells you the "focal length" of the lens.

Focal lengths between 40 mm and 60 mm are called "normal". This is approximately the way our eyes see the image.

Focal lengths less than 40 mm are called "wide angle". This gives a wider view than our eyes, but the details appear smaller. The lower the number, the wider and smaller the image appears.

Focal lengths greater than 60 mm are called "telephoto". This gives a narrower view than our eyes, but the details appear bigger. The higher the number, the narrower and bigger the image appears.

For a zoom lens, a range of focal lengths are given. These correspond to the shortest wide angle and the longest telephoto image the lens can provide.

Most digicams come with a zoom lens close to 35mm-105mm. This provides a little wide angle and a little telephoto, to give the casual photographer some flexibility for everyday pics.

To simplify the marketing, they divide the telephoto number by the wide angle number (105 divided by 35) and call this a 3x zoom.

Serious photographers often want a wider range and will get a camera with a 12x zoom like 35mm-420mm. Or get an SLR camera that takes removable lenses and get several different zoom lenses.

Good Luck

Answer 2

These are zoom lens parameters. Foir example a lens with a capability of 75-300mm can zoom this range in bringing things closer.

Answer 3

Those are parameters of depth of field.