Canon Camera Lens Buying Guide

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Canon Camera Lens Buying Guide

Canon is widely regarded as one of the world's leading camera and lens manufacturers, and its products have for many years been the favoured choice for many professional and amateur photographers. In 2010, Canon held an almost 50 per cent market share in digital SLR cameras worldwide. An extensive range of lenses are available from the current range as well as many previous models on the pre-owned market.

About Canon Lens Mount Types

Canon introduced their first SLR camera in 1959, and as lens and camera technologies have developed along with advancements in the fields of exposure automation and automatic focusing, new lens mounts have been introduced, the mount being the standardised mechanical interface between the lens and the camera body.
The first was known as the R mount, and was in use until 1964. This style of mount had a number of extended pins and levers protruding from the rear of the lens to connect with the stop-down mechanism of the camera.
From 1964, the Canon FX camera utilised the FL mount, which modified the extended pin system (this had been a weak point on the R mount), and was designed for smoother coupling between lens and body. R series lenses are compatible with FX bodies and vice versa.
With the growth of electronics usage in SLR cameras, 1971 brought an initial series of 14 lenses with the FD mount. This series allowed full-aperture exposure metering through the lens. The FD mount was modified in 1976 to dovetail with the launch of a new range of auto-exposure cameras (the AE series). FD series cameras can use the previous FL range of lenses with some limitations.
The Canon EOS (Electro-optical system) range of cameras and lenses was first introduced in 1987 with 35mm film cameras and continues with their various models of digital cameras and compatible lenses. The EF mount introduced at this time brought about a compatibility break with the previous FD mount, rendering the FD all but obsolete for the mainstream market. EF stands in this case for Electro-Focusing, with automatic focusing handled by a motor within the lens. Unlike previous lens styles, there is no mechanical linkage between the lens and camera, all focusing and aperture control being passed via electrical contacts on the lens mount. A number of acronyms will be found when browsing these lenses, signifying various developments and enhancements. These include USM (Ultra Sonic Motor), IS (Image Stabiliser) and DO (Diffractive Optics).
The EF-S is a derivative of the EF mount, strictly for use on Canon's range of cameras with APS-C sensors. EF lenses can be used with EF-S bodies, but EF-S lenses are incompatible with EF bodies.
A further derivative, the EF-M was designed specifically for use with Canon's Mirrorless Interchangeble Lens Cameras (MILCs), a style of camera with interchangeable system lenses, but lacking the mirror and pentaprism viewfinder of a full-size SLR. EF and EF-S lenses can be used on EF-M cameras with the use of a mount adaptor.

General Lens Specifications

There are, broadly speaking, three basic factors that define the specifications of lenses;


The maximum aperture specification for the lens indicates the amount of light which it will pass to the camera's image sensor. This is shown as an f number in the lens specification. Wider apertures are indicated by smaller f numbers, and the lower the f number, the more light the lens will pass. This affects how the lens will perform in low-light conditions, and the shutter speed in those conditions may also be limited or affected by this limitation. Standard and wide-angle lenses tend, due to their simpler construction, to have wider apertures than telephoto and/or long focal-length zoom lenses.
Specification of maximum aperture specification is in terms of f stops, such as f/2, f/4, f5.6 etc.

Focal Length

The focal length of a lens defines its magnification. A wider view of a subject will be provided by a lens with a short focal length, whereas one with a longer focal length will show a narrower view of the subject. When 35mm film was the dominant photographic medium, definitions of wide, standard, and telephoto lenses were made relative to the standard 35mm frame size. The image sensors fitted to digital SLR cameras are in most cases smaller than this, and hence, a lens of the same focal length will draw in more of the subject as its focal length will now be larger in proportion to size of the image sensor. Some premium digital SLRs are now fitted with full-frame sensors, of the same size as a standard 35mm frame.
A lens with a fixed focal length is known as a prime lens, one with a variable focal length is a zoom.


When 35mm film cameras dominated the mainstream market, the frame size remained unchanged, and so any lens of approximately 28mm focal length was regarded as a wide-angle, a standard lens was one of 50mm or so, and telephotos were anything of 85mm and above. These days, the size of image sensors in digital SLRs can vary between makers and models and has not been standardised in the way that the 35mm frame was. Therefore, as the combination of focal length and sensor size determines the angle of view, there is no fixed relation between angle of view and focal length. The promotional literature or specification sheets for lenses will, in many cases, specify a 35mm equivalent focal length, allowing the photographer to compare any lens to what is regarded as the traditional focal lengths.

Current Lens Ranges


The EF range offers a wide selection of zoom, telephoto, wide angle, and specialist lenses, suiting all applications and all budgets

Zoom Lenses

EF zoom lenses span the full range of focal lengths, through wide, standard and telephoto zoom options. Wide zooms are available from 8-15mm to 17-40mm ranges, with maximum apertures varying from f/2.8 to f/4. The standard zooms range from 17-85mm to 28-135mm focal lengths, with maximum apertures as wide as f/2.8. Telephoto zooms come in a number of ranges, with spanning focal lengths from 28mm to 400mm, again with maximum apertures as wide as f/2.8.

Wide Angle

Fixed-length wide angle and standard lenses cover the 14mm to 35mm range. Wide angle lenses are generally suitable for landscape photography.

Standard and Medium Length

The range of standard and medium length prime lenses spans the 40mm to 100mm range, and would typically be used for general and portrait photography.

Long-focus or Telephoto

The long-focus lenses cover 135mm to 800mm focal lengths, the longest of these being ideal for the wildlife photographer.


The range of specialised lenses includes a pair of tilt and shift models, typically used by the professional to correct converging verticals in building photography, and macro lenses, intended for close-up work.


The current EF-S range extends to 10 models of mainly zoom lenses, with focal lengths ranging from 10-22mm up to 55-250mm.


The EF-M range is the most limited of the Canon ranges, with one 18-55mm zoom lens, and a 22mm wide-angle.

Historic Lenses

With a history of lens manufacture spanning over 50 years, any detailed examination of Canon's past products is probably out with the scope of this article. The purchase of a lens for a specific vintage camera should initially be guided by the history of lens mounts shown above in order to match lens to camera and then by the photographer's requirements with regard to focal length and maximum aperture.


A Canon lens is sure to be a good investment and should be expected to hold its value well on the pre-owned market. While they continue to make a wide range of market-leading lenses specifically for their digital cameras, a number of the pre-digital lenses from the film camera era are still compatible, subject to some limitations, with the current Canon digital bodies. A careful pre-owned choice should yield a lens which will give many years of service and hold its value well.

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