Lens Nomenclature Decoded

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Have you ever looked at the text printed on the barrel or around the front element of your lens and wondered what all those numbers and letters and symbols meant? Some may be clear and obvious, some more obscure. Here’s a “decoder ring” of sorts, to help you sort it all out.

Let’s take a Canon lens as the first example:

Canon Lens EF 28-80mm 1:3.5-5.6. Ø58mm
- “EF” stands for “electrofocus”. This means the lens has an internal motor for auto-focusing cameras.
- “28-80mm” refers to the focal length that the camera is capable of. In this instance, 28mm is the widest the camera can achieve, and 80mm is the longest distance it can achieve. The fact that there is a range indicates that this is a zoom lens.
- “1:3.5-5.6″ refers to the widest aperture the lens is capable of achieving. The fact that there is a range, “3.5-5.6″, indicates that this is a zoom lens (a prime lens would have a single number referenced). The “1:” is included as the aperture measurement is considered a ratio.
- “Ø58mm” indicates the filter ring diameter. This is the size filter that would screw onto the end of the lens and indicates the lens diameter.

Canon Lens EF 200mm 1:2.8L II USM. Ø72mm
- “EF” – EF lens type.
- “200mm” – Fixed focal length of 200mm – a prime lens.
- “1:2.8″ – A fast, prime lens.
- “L” – Indicates Canon’s “luxury” lens line.
- “II” – Indicates this is Canon’s second version of this particular line of lenses.
- “USM” – Indicates this particular lens has the “ultrasonic motor” auto-focusing motor type.
- “Ø72mm” – The filter size that fits on the end of the lens.

Now let’s talk about the Nikon Nikkor lenses:

Nikon AF-S DX Nikkor ED 18-55mm 1:3.5-5.6GII
- “AF-S” – Auto-Focus Silent Wave Technology (ultrasonic focusing motor).
- “DX” – The DX lens type (a smaller image circle lens).
- “ED” – Extra low dispersion. This type reduces color aberrations at the high end of a zoom lens range.
- “18-55mm” – The focal length that the camera is capable of.
- “1:3.5-5.6″ – The widest aperture the lens is capable of achieving.
- “GII” – Second-generation G-type lens, which has no aperture ring on the lens.

Nikon Nikkor-S Auto 1:1.2 f=55mm 230478
- “-S Auto” – Auto-Focus Silent Wave Technology (ultrasonic focusing motor).
- “1:1.2″ – A very fast prime lens with a fixed f/1.2 aperture.
- “f-55mm” – Fixed 55mm focal length
- “230478″ – The serial number of the lens. Here is a chart that describes what the different serial numbers indicate.

Now, lets talk about Canon lens categories:

EF lens – “EF” stands for “electrofocus” and was established for auto-focusing cameras.
EF-S lens – “EF-S” stands for “Electro Focus, Short-back Focus”. There is a smaller imaging circle within the lens, which allows the lens to be made with less actual glass (and therefore with less cost) – all of the lens elements can be smaller for a given focal length and maximum aperature.
L series lenses – The “luxury” line of Canon lenses. They are the most expensive and highest quality of their lens lines.
IS lenses – “IS” stands for “image stabilization”. The lens automatically “stabilizes” the image when shooting at lower shutter speeds, to reduce blur.
MP-E – Manual focus macro lens type.
TS-E – Tilt-shift manual focus lens type.

Any Canon EOS camera with a red dot on the lens mount can take EF type lenses. Any Canon EOS camera with both a red dot and a white square on the lens mount can take both EF lenses and EF-S lenses. Here is a great FAQ about Canon lenses from a beginner’s standpoint.

Now for the Nikon Nikkor lens categories:

AF – Auto-focus lens
AF-S – Auto-focus, short-back lens
AF-S DX – Auto-focus, short-back lens specific to the Nikon DX Digital Camera line.
PC – Manual focus macro lens
PC-E – Manual focus

Here is a great Nikon lens nomenclature chart for your reference.

Photo credits (in order of appearance):
- “Canon EF 24-105mm f/4 L IS USM” by Stage 88 on Flickr Creative Commons.
- “Caught in the Nikon lens” by Tiffany Day on Flickr Creative Commons.

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  • Melinda B.

    This was helpful, I shoot Canon and have always wondered about what the numbers all meant.

  • Tim Fogarty

    Thanks for the ‘decode’ — just bought a Canon DSLR and hadn’t figured out what USM ES, L (and the like) meant. This article will be very helpful for future lens purchases — thanks for taking the time to write it! You are one of the people who exemplify what the internet CAN be — a nurturing world community where people express their passions and share genuinely useful information — much appreciated!