35mm equivalent lens

Understanding digital camera focal lengths

Zoom lensMost people are familiar with focal lengths of 35mm camera lenses. Digital camera manufacturers describe focal lengths in terms of the lens length on a 35mm camera that will produce a similar area of view.

Focal length on one 35mm camera is the same for all others because the size of the film each uses is the same. Digital cameras, however, have different focal lengths because the size of their image sensors vary from one camera to another.

Expressing focal lengths in terms of 35mm equivalent makes it easier for individuals to understand so they can compare digital camera lenses.

For example, here are focal lengths for a Nikon 5400 digital camera with a wide angle to short telephoto zoom, and the 35mm equivalent:


Nikon 5400


Normal *



Wide angle






Zoom lengths are not all equal

It’s important to realize that a 3x optical zoom on one digital camera may not give the same magnification as another with a 3x zoom. The Nikon 5400 has a 4x zoom, which when fully zoomed has a 116mm equivalent focal length. But Nikon 5200, which has a 3x zoom, has a 115mm equivalent focal length. Not much difference yet one is 3x and the other is 4x.

When buying a compact digital camera, it’s important to ask the 35mm equivalent if looking for a specific focal length.

Digital single lens reflex camera effective focal lengths

Many DSLRs have a crop factor, known as Focal Length Multiplier, which must be calculated to understand the effective focal length of a given lens. For example, a 250mm lens with a FLM of 1.6 has the effective range equivalent to 400mm.

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