Understanding EF Lens Naming Terminology

Understanding EF Lens Naming Terminology

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Understanding EF Lens Naming Terminology

The name of every Canon EF Lens is made up of a bunch of numbers and letters that tell you something about the lens. By making sense of the naming formula, you can instantly get to know the characteristics of different lenses. Basically, a lens name comprises 4 components indicating the lens type, focal length, maximum aperture and other features, listed in the aforementioned order. The following article will take EF-S 10-22mm f/3.5-4.5 USM lens as example to introduce and explain the naming terminology of Canon lenses.
Different components in the naming formula: EF-S 10-22mm f/3.5-4.5 USM
What it stands for: Lens Type Focal Length Maximum Aperture Other Features

Lens Type

The first component in a lens name, for example EF-S, is the letter code that defines the lens type. Five different types of lenses are produced by Canon, including EF, EF-S, EF-M, TS-E and MP-E. Among those, EF (figure 1) series lenses offer the highest compatibility and can be used with all EOS DSLR cameras.
EF 24-70mm f/4L IS USM(Figure 1)
EF-S (figure 2) means the lens is designed for use with EOS DSLR cameras using APS-C sized sensors. S refers to the Small Image Circle design.
EF-S 10-22mm f/3.5-4.5 USM(Figure 2)
EF-M (figure 3) refers to lenses dedicated for the EOS M digital camera. All EF-M lenses on the market feature a Stepping Motor (STM) for fast, quiet and smooth continuous AF in Live View shooting
EF-M 18-55mm f/3.5-5.6 IS STM(Figure 3)
TS-E (figure 4) refers to Tilt-Shift lenses. T and S are the abbreviations of Tilt and Shift respectively, referring to the capability of tilting or shifting part of the lens elements in the optical construction in order to change the focal plane and correct perspective distortion.
TS-E 17mm f/4L(Figure 4)
The MP in a MP-E lens (figure 5) is the abbreviation of Macro Photo. This letter code is used in the naming of MP-E 65mm f/2.8 1-5X lens which has a maximum magnification of 1x or above. You can tell from its name that the lens is used in the realm of macro photography.
MP-E 65mm f/2.8 1-5X(Figure 5)

Focal Length

The numbers following right after the lens type code represent the lens’ focal length. A prime lens has a single focal length such as 85mm. A zoom lens has numbers indicating a zoom range, for example 10-22mm where 10mm is the wide-end and 22mm is the tele-end of the lens. A smaller number means a wider angle of view capable of capturing a wider scene and a lens has focal length 35mm or less is considered as a wide-angle lens. A larger number refers to a narrower angle of view capable of capturing distant subjects and a lens has focal length 70mm or above is considered as a telephoto lens.
Different zoom ranges

Maximum Aperture

Numbers like f/3.5-4.5 stand for the maximum aperture value of a lens. The larger the aperture, the more the lights can enter the lens, and this is represented by a smaller f-number. A larger aperture can result in a brighter image, allowing the use of a faster shutter speed or creation of defocused background. On the contrary, the larger the f-number, the smaller the aperture. The amount of lights that can enter the lens is reduced, thus resulting in a slower shutter speed and wider depth of field. There is only one maximum aperture value for prime lens and normally two for zoom lens, corresponding to the lens’ shortest and longest focal lengths respectively. Take 10-22mm f/3.5-4.5 as example. It has a maximum aperture of f/3.5 at 10mm and f/4.5 at 22mm. Some lenses have the same maximum aperture throughout the focal ranges, and those are called “Fixed Aperture”. For example, the fixed apertures for EF 24-70mm f/2.8L II USM and EF 24-105mm f/4L IS USM are f/2.8 and f/4 respectively.

Other Features

The name of a lens not only tells us about its focal length, maximum aperture and type, but also its characteristics and features. EF lenses incorporate a host of cutting-edge technologies such as STM and USM. We can tell if a lens offers any of these features from the last component of its naming formula. This can help users understand and select the right lens that suits their needs. Below introduces some of these lens’ features.
Special Feature or Type:L
L, a prefix of Luxury, is the name of Canon’s high performance lenses which can be identifiable by a bright red ring around the lens barrel. The L series lenses meet stringent standards of performance, using special optical materials including fluorite lens (an artificial crystal), precision-ground aspherical lens element, UD (Ultra-low Dispersion) or Super UD lens elements to realize unrivaled quality.
Special Feature or Type:USM
USM stands for Ultrasonic Motor, which uses ultrasonic vibrations to generate rotational force. It has a very simple construction consisting of an Elastic Stator and a Rotating Rotor. Without the need for a gear train, it realizes silent operation. A high-torque output means quicker starting and more precise focusing.
Special Feature or Type:STM
This letter code refers to lenses that adopt a Stepping Motor (STM). STM is a motor mechanism that drives its rotation by electric pulses. It features a simple and reliable structure and provides the benefits of high responsiveness and precise control. It also supports full time manual focusing.
Special Feature or Type:DO
This refers to lenses featuring multi-layer diffractive optics (DO). DO elements make use of the diffraction phenomenon to control the direction of lights. The use of one DO lens element is sufficient to correct various types of aberrations effectively, as well as to make a lens smaller and lighter.
Special Feature or Type:IS
"IS stands for Image Stabilizer. It can counteract camera shake to ensure image sharpness. For image shake occurs in both the horizontal and vertical directions, the Optical Image Stabilizer lens group can shift vertically and horizontally on a plane perpendicular to the optical axis to counteract the image shake, resulting in blur-free images.
The above explanation of the 4 naming components aims to provide a clearer picture for photo enthusiasts to understand how a lens is named and classified by Canon according to the lens’ specification, functions and technologies. Other naming codes such as “II or III” simply represent the second or third generation of lens with the same optical construction. “Fisheye” is the name of a specialized lens which can create fisheye effect with 180? angle of view. For this type of lens which offers multiple lens’ features, those corresponding codes will be listed at the end accordingly.
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