Focal Length Calculator

35mm equivalent Focal Length Multiplier Calculator
This calculator allows you to calculate the 35mm equivalent Focal Length for digital camera at specific sensor size.

Focal Length and Angle of view. The focal length of the lens is the distance between the lens and the image sensor when the subject is in focus, usually stated in millimeters (e.g., 28 mm, 50 mm, or 100 mm). In the case of zoom lenses, both the minimum and maximum focal lengths are stated, for example 18–55 mm.

The shortest focal length, or "ultra wide-angle"lenses, range from 14mm to 20mm, and are followed by "wide-angle" lenses from 24mm to 35mm, and then "standard" lenses from 45 to 70mm, which are similar to the field of view of the human eye.

Angle of view. In photography, angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera. It is important to distinguish the angle of view from the angle of coverage, which describes the angle range that a lens can image. 

Certain digital cameras require a focal length multiplier in order to ensure the photographer is getting the angle of view they are expecting. This only became a factor when photography transitioned from film to digital and changes were made to many DSLR cameras that affected the focal length of common lens sizes.

When pairing a digital camera with a lens, it is important to know whether or not a focal length multiplier needs to be considered.

It could dramatically affect the lens that you purchase because you could be buying a lens that does not meet your specific needs.

A full-frame sensor has dimensions of 36mm x 24mm. If your sensor is smaller than that, you need to calculate your focal length multiplier and apply it to the focal length of the lens you’re using to get the 35mm equivalent focal length. You may also see the focal length multiplier referred to as the crop factor.

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