Glossary

35mm equivalent lens

Written by Gail Bjork

Why digital camera focal lengths are described in terms of a film camera

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:

Lens

Nikon 5400

35mm
equivalent

Normal *

14.5mm

50mm

Wide angle

5.8mm

28mm

Telephoto

24mm

116mm

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.

About the author

Gail Bjork

Gail Bjork, who is passionate about digital photography, is the owner and editor of Digicamhelp.Gail is the author of three illustrated ebooks about digital photography. A number of her photos and digital photography related articles appear at other websites.In 2006, a series of her photos, People in the Louvre, were exhibited at the Underground Photo Gallery
in Iisalmi Finland. Eight of her photos taken in the Florida scrub are on permanent exhibition at Parrish Medical Center in Titusville, Florida.Gail served twelve years as an elected member of The School Board of Palm Beach County, Florida, one of the largest school districts in the U.S. She has also been the editor of a small town newspaper and a free-lance writer. Gail and her husband owned and ran several small businesses.

7 Comments

  • Hey kevin try this on Wiki, for W/A lens and depth of field the  Frazier lens. i met the man in the 1990’s and saw his work.

  • have a 35mm minolta maxxum qt si with 2 lenses af 35-80 &af 70-210 wondering if there is a digital camera that would convert to these lenses, or should I just invest in a digital camera with the lenses already.

  • why can’t someone just make a 35mm cam that functions like a digital when the film isnt it it? i am not a phtog. or prof. just a girl wishing i could take digital pic’s like a 35 mm when i want to. isnt there something out there for beg/interm. where its a good digital with a great zoom lense with  feel of a 33mm etc.? Or, can someone recom. a good digital with lots of zoom or night features and a good 35mm cam that i can grow with? why cant they just invent a piece of hardware that lets you can the lenses from dig. to 35mm and put in the film……
    you know?????

  • You may have to look at a high end camera such as the Canon EOS 5D Mark II. It has a 21MP CMOS sensor and includes full 1080p HD movie recording. The HD video capture allows users to shoot uninterrupted at full 1080 resolution at 30fps The lens you use, too, will have an impact on the depth of field. DSLR video is still in it’s infancy and does not yet have the full capabilities of a dedicated camcorder.

    You may want to try a place like B&H Photo & Video.



  • Yea, I still use film, as I have yet to find a digital still or video  camera that can produce  an effective f-stop (no, NOT t-stop) of 1448 for super-incredible-extreme-unmatched depth of field.  I do not know of any processor for a digital camera that can do this as yet.  As I do a lot of effects work, let me know!!!!!!!

  • When discussing the effective focal length of a DSLR lens on a camera with less than full frame sensor, isn’t it important to note that the 250 mm lens with an RLM of 1.6 yielding a 400 mm “effective focal length” is effective in angle of view only, not in optical factors like depth of field at any given focus distance, which has not changed with the smaller sensor.