2013-03-28

Making sense of camera lens names


Photography can be confusing at times, with a myriad of baffling terms and acronyms to trip up the unwary. This is particularly true of lenses, with manufacturers seemingly competing to have the longest and most elaborate names.

If you’re looking to extend your lens collection, the extensive range of models available can make it a daunting prospect. But that also means you have plenty of choice, and in this blog we’ll try to arm you with a little knowledge that will help you navigate through the confusion, and choose the right lens for you.


What’s in a name?
At first glance, the full name of a lens can be overwhelming. Panasonic LUMIX G X VARIO PZ 45-175mm f/4.0-5.6 ASPH POWER O.I.S. anyone?

However, what might at first appear to be a random collection of numbers and acronyms designed to confuse, the name provides you with clear details about its features and performance.

Numbers Game
In an ideal world, manufacturers would use similar terms for features like Image Stabilisation, but trademark legislation means they tend to adopt different names for similar features. One common approach though is in their use of numbers. These are vital signposts for the lens buyer and tell us the focal length and aperture range of the lens, which in turn reveal its capability and quality level. In the case of the aforementioned Panasonic, we can deduce from the 45-175mm f/4.0-5.6 that it’s a zoom lens, with a focal length range from 45-175mm. Convention also tells us that it has a variable aperture range too, with a maximum aperture of f/4 at the wide end (in this case 45mm) and f/5.6 at the longest end of the zoom (175mm in this example). Make sense?  

So a range of numbers for the focal length indicates a zoom lens, whilst a single number indicating a fixed focal length, or prime lens. Similarly, if a zoom lens has a single number for the aperture then we know that the lens has a constant maximum aperture throughout its zoom range. These lenses are generally larger, heavier and considerably more expensive than comparable models, and professional photographers in particular are normally keen to have the same maximum aperture throughout the zoom range. Fixed focal length lenses only ever have one aperture value.

A notable exception to this convention are the Carl Zeiss range, which show the maximum aperture first, then the focal length. As is customary in their native Germany, they use a comma rather than a full stop in their aperture value, so a 25mm f/2.8 from Zeiss would be displayed as 2,8/25.

Alphabet Soup
So having unravelled the numbers, that just leaves the letters. Typically these will tell us about the quality level or model range to which the lens belongs, plus any key technologies relating to the optics, motor, image stabilisation, plus any subjects for which the lens is particularly adept, like Macro shooting for example.

In the case of the Panasonic LUMIX G X VARIO PZ 45-175mm f/4.0-5.6 ASPH POWER O.I.S., the first part tells us that it’s designed for the LUMIX G Series, it’s part of Panasonic’s flagship X series, and that it features a Power Zoom switch on the lens to operate the zoom electronically.

The letters at the end of name indicate that the lens utilises aspherical lens elements (which are used to enhance the optical quality), and that it features Panasonic’s Power Optical Image Stabiliser, to help keep the lens steady.

That gives you a picture of the lens naming conventions, let’s look at some of the letters used by particular brands.

Canon Naming Convention
Canon’s lens naming is fairly easy to follow. The lenses will start with a prefix to show the type of lens it is; EF stands for Electro Focus, EF-S is for Electro Focus with Short back focal design, EF-M is for Electro Focus Mirrorless, MP-E is for Macro Photography for EOS and TS-E is for Tilt Shift for EOS. The F in EF or EF-S denotes that the lens has a focus motor and can be automatically focussed by an EOS camera. Lenses without the F, such as the MP-E and TS-E do not have a focus motor and must be focussed manually.

Models with an L in the name after the aperture, such as the EF 50mm f/1.2L USM, are part of Canon’s flagship L series range, made using the very finest optical systems and designed for professional use. The L stands for Luxury and means that the lens is of a more durable construction, and in many cases are resistant to dust and water ingress. These lenses have a tell-tale red stripe around their lens barrel and the larger telephoto lenses use the distinctive white paint, so prevalent at major sporting events.

Canon also use letters such as USM, STM, IS, DO, Macro and in some cases Roman numerals. USM and STM describe the focus motor used by the lens, either UltraSonic Motors or the more recently introduced STepper Motor technology. Models without either utilise a more basic DC motor. IS denotes that the lens has a built-in Image Stabiliser to counteract the effects of camera shake. DO indicates that the lens employs Canon’s innovative Diffractive Optics, which is also signalled by the distinctive green stripe around the lens barrel. 

Finally, the Roman numerals like that seen in the EF 70-200 f/2.8L IS II USM, denote the lens version. The Roman numerals indicate that this is the second version of this popular lens, introduced in 2010. Canon periodically update lenses with the new versions bringing enhancements in performance, construction, size or weight.

Nikon Naming Convention
Nikon’s naming convention is similarly easy to follow. Most lenses begin with either AF or AF-S, both are autofocus lenses, the latter is the more modern incarnation which features a Silent Wave Motor, for fast, near-silent focusing. The numerals follow the principles we established earlier, and Nikon also use various letters to indicate particular features, such as VR or VR II for Vibration Reduction (their image stabilisation system, the VR II indicating their second generation system). IF denotes a lens with Internal Focusing, where the lens will not extend during focus adjustment, ED identifies Extra-low Dispersion glass has been used in the construction.

The letter D appears with some older AF lenses and indicates that the lens passes distance information through to the camera. Micro is Nikon’s description for lenses with Macro capability. Many newer Nikon lenses have a G in their name, which is short for Gelded. Historically Nikon included an aperture ring on their lenses, but in most modern camera systems, aperture is controlled from the body and so the aperture ring is superfluous. The G indicates that is has been removed.

Finally, Nikon use the DX nomenclature to identify their lens designed for APS-C sensor bodies. These can still be used on full-frame (or FX) bodies, but the sensor switches to 1.5x crop mode at the same time. In 2011 Nikon also introduced the CX naming for their Nikon 1 Series of compact system cameras.

Hopefully we've armed you with some knowledge that will help you understand more about your current lenses and prove useful when looking to add to your collection.

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