The Complete Guide to Buying a Camera Lens

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The Complete Guide to Buying a Camera Lens

All cameras have at least one lens that is either incorporated into the main body or attached separately. This is a guide to buying the separate kind of camera lenses.

About Camera Lenses

A single lens reflex (SLR) camera is technically defined as one that uses a mirror and prism system to capture images. This means that what is seen through the viewfinder is what will come out in the photograph. Perhaps the most important feature of an SLR, however, is that unlike a compact camera (for example, the ones on phones), the lens is separate from the camera body. This makes SLR much more versatile. Photographers can begin with just one multipurpose lens (usually a zoom lens that can make objects appear closer or further away) and then add more specialised lenses to their collection later. But what exactly is a lens, and what does it do? An optical lens is defined as an object that transmits beams of light and may change the direction of the beam, a process known as refraction. Camera lenses are optical lenses, or collections of optical lenses, that are used in the production of a photographic image.

Choosing Camera Lenses

For photographers who are new to SLR photography, there can appear to be a baffling array of different lenses and different technical terms to get to grips with. Here is a guide to what it all means.

Types of Camera Lens

The following table explains the main types of lenses and what they are typically used for.


As the name suggests, this is for photographing subjects which are close to the camera. Technically, it is any kind of lens that produces an image the same size as or larger than the subject itself.

Close-ups of small animals, insects, plants etc.


Another name for a macro lens.

See above.



A telephoto lens has a long focal length, allowing the photographer to capture clear images of objects that are far away.

Capturing sporting and cultural events and wildlife photography.

Wide angle

A lens with a short focal length, allowing the photographer to capture wide expanses.

Landscapes, architecture.


A specialty lens that produces an image with such a wide angle that it’s distorted, with the centre seeming to bulge outwards.

For making interesting arty images. Also often used for photographing extreme sports.

Tilt / Shift / Perspective lens

Shooting a tall building usually requires the camera to be tilted, causing a distortion to the image. A perspective lens allows the photographer instead to use an untilted camera.

Tall buildings.


This allows a standard lens to be converted into a telephoto lens.

Capturing sporting and cultural events and wildlife photography.


Any lens with a focal length that can vary; in other words, it can zoom in and out. For photographers using only one lens, this is almost always the best choice.

A standard, all-purpose lens

Why Is There a Figure in Millimetres in the Lens Description?

Descriptions of camera lenses often contain a figure in millimetres (mm). This refers to the focal length, or range of focal lengths, the lens provides. Under around 35mm and it’s a wide angle lens; over 70mm and it’s a telephoto lens. Figures between these two extremes are for standard lenses, useful for general photography.

What’s the Difference Between Film and Digital Camera Lenses?

Nowadays, most people looking for a new camera, whether SLR or compact, will choose a digital model. The advantages are obvious: no need for expensive film or to send photos away to be developed. Simply use a memory card, and download onto a computer when it gets full. There are technical differences between lenses designed for film cameras and those designed for digital cameras, but they can sometimes be interchangeable. It’s usually easier to use a film camera lens on a digital camera than vice versa. But never rely on it being possible; always do the research to make sure the lens being bought is compatible with the specific model of camera it will be used with.

Focus: Manual, Auto or Both?

The focus refers to how to ensure the image is sharp. If a lens has manual focus, then the photographer has to turn the lens to get the photograph correct; if it’s auto, this happens automatically. Some lenses give both options. The advantage of manual focus is that it gives more control. It’s possible to get special effects by using non-standard focus. The advantage of auto focus is that there’s no need to worry about blurry images. This is great for people who want to get out their camera and take a photo quickly.

What is the Crop Factor, and How Does it Affect Which Lens to Buy?

The crop factor or focal length multiplier is a specific term used with digital cameras. It refers to the size of the sensor in comparison with that of a standard (35mm) film camera. A camera with a crop factor greater than one will only capture the middle part of what a film camera would have captured; the greater the crop factor, the smaller that part. There are both advantages and disadvantages to having a high crop factor. For example, all cameras give a sharper image in the middle part, and with a camera with a high crop factor therefore, only the good bit appears as the final image. Conversely, wide angle lenses are not nearly so effective on cameras with a high crop factor.
There are lenses specifically designed for crop factor cameras; for example, the Nikon DX range and the Canon EF-S.


The aperture of a lens refers to the size of hole letting light into the camera. Specifications for lenses usually give a minimum and maximum aperture available. This is usually given as an f-number, which relates focal length to effective aperture diameter, which means high numbers (confusingly) signify a small opening, and low numbers a large opening. Lenses with low f-numbers, and therefore wide apertures, are also known as fast. This is because the wider the aperture, the less time needed to let the required amount of light through. This makes fast lenses particularly good for capturing sharp images of moving objects.

Different Brands of Lenses

There is no widespread agreement on what the best and worst lens makers are although many photographers have their own personal preferences. Canon and Nikon are often particularly highly regarded, and they certainly have particularly wide ranges of lenses available. Fujifilm is a favourite with many. They have a smaller range, but some people think better quality. However, most photographers would say it’s far more important to pay attention to the specification of lenses than to who manufactured them.

New or Used?

Unlike some other kinds of equipment, there is no significant disadvantage to buying used rather than new camera lenses, so this can be a good way to pick up bargains. It’s a good idea either to try them out before buying or to buy from a dealer or online auction site that offers a guarantee in the event that the lens isn’t as described, however. On the other hand, technology is changing at such a fast pace that it can be difficult to get second-hand lenses with the same features and high specification as new ones.


Although at first the technical specifications of camera lenses can seem difficult and confusing, it’s not difficult to get to grips with the terminology. Once that’s done, making a list of essential and desirable features in a new camera lens is a good starting point to buying one. One of the delights of photography as a hobby is the fact that it can be pursued with a simple, inexpensive range of equipment which can then be expanded over the years. For many amateur photographers, acquiring a collection of lenses is part of the allure, whether that means browsing through specialist photography shops or scouring the listings on online auction sites.

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