Camera Lenses

 

There are many things that determine the quality of your photography, and one of the most important is the lenses you use. A good camera lens will capture sharp photos with plenty of detail and contrast, while a poor one can leave your images looking dull and blurry.

When shopping for lenses, it's important to consider the types of subject you intend to shoot, the likely lighting conditions, and of course your budget. There is no single lens that is perfect for every situation, so you'll need to balance the pros and cons of the various options and pick the best compromise.

This guide will help you make these important decisions so that you can find a camera lens which suits all of your needs, both artistic and practical

Types of Camera Lens

There are dozens of different types of lens available, designed for use in a wide range of circumstances. However, they can largely be grouped as follows:

Standard Lenses

 

A standard lens is one with a mid-range focal length, typically around 50mm. They have an angle of view which is roughly the same as the angle that the human eye can comfortably view, meaning that they produce images which appear "natural" to the viewer.

Standard camera lenses usually have a fixed focal length and wide aperture, giving them excellent performance in low light. They are popular for a wide range of photography subjects, including landscapes, portraits, and candid shots.

Macro Lenses

 

A macro lens is one designed especially for close-up photography. They have a different internal construction from normal lenses which gives them very good sharpness and contrast, meaning that they produce some really eye-catching photos.

Macro lenses are useful for photographing any subject at very close range. Typical subjects include insects, animals, and plants, but they are also popular for taking extremely detailed photos of everyday objects.

Telephoto Lenses

 

 

A telephoto lens has a long focal length and provides a high level of magnification, allowing you to photograph subjects at a moderate to far distance. They tend to be bigger and heavier than other types of lens, although modern technological advances have made them more compact and easier to handle.

Telephoto lenses are popular for any type of photography where you can't get near to the subject, including wildlife and sports events. They are also commonly used in portrait photography, where a moderate telephoto lens will provide a natural, undistorted perspective.

Wide Angle Lenses

 

A wide angle lens is one with a short focal length. They provide an angle of view beyond that of a standard lens, allowing them to capture more of the scene in a single shot. Extreme wide angle lenses are known as fisheye lens; these can capture around 180 degrees, making for some intriguing, almost abstract photos.

Wide angle lenses are useful for photographing landscapes, cramped interiors, and other subjects which won't fit into a normal lens's field of view. Fisheye lenses take this even further, and are popular for photographing action sports like skateboarding and surfing, where their inherent distortion gives photos a dynamic feel.

Specialist Lenses

Finally, there are a number of specialist camera lenses which cater for less common photography needs. These include tilt and shift lenses for perspective control, soft-focus lenses for portrait photography, and infrared lenses for capturing light outside the normal spectrum.

A specialist lens is used to produce some sort of special or creative effect, and so they have limited use in general photography. However, they can be very useful if you need to photograph a particular subject in a particular way.

Kit Lenses

Many entry-level SLRs come bundled with one or two lenses, often called "starter" or "kit" lenses. These are good for getting you up and running quickly but they are generally very cheap, slow lenses with poor image quality.

A kit lens is great for getting to grips with your camera and figuring out what focal lengths you like using, but you should consider replacing it when your budget allows.

Focal Length

The most important factor in any camera lens is its focal length. This determines which type of lens it is, and what subjects it will be able to photograph. Focal lengths range from just a few millimetres up to over a metre, and can be loosely grouped as follows:

Lens focal lengths, types, and uses 

Lens focal lengths, types, and uses 


Focal Length Lens Type Common Subjects
8mm - 24mm Ultra wide angle (fisheye) Wide panoramas and skyscapes, artistic
24mm - 35mm Wide angle Interiors, architecture, landscapes
35mm - 85mm (50mm common) Standard General purpose
85mm - 135mm Short telephoto Portraits, candid
135mm - 300mm Medium telephoto Close sports, action
300mm+ Super telephoto Far sports, wildlife, nature, astronomy

Crop Factor

Lens focal lengths are specified for a camera with a "full-frame" 35mm sensor. Most consumer DSLRs and all compacts use a smaller sensor, and this has the effect of cropping off the edges of the photograph, resulting in an image which is more "zoomed in" than it would be on a full-frame sensor.

This cropping makes it seem as though the lens has a longer focal length than it really does. We can calculate a lens's "effective focal length" by multiplying the real focal length by the camera's "crop factor". A typical crop factor is around 1.5x, meaning that a 50mm lens actually has an effective focal length of 75mm when fitted to this camera.

Before buying any lens, you should find out your camera's crop factor and use it to calculate the lens's effective focal length. This will ensure you end up with a lens which gives the desired effect.

Prime vs Zoom Lenses

A "prime" lens is one with a fixed focal length, while a "zoom" lens is one that can zoomed in and out to provide a wider range of focal lengths. Each type has its own benefits and drawbacks.

Prime lenses tend to have better optical quality than zooms, and can usually achieve a wider aperture, giving them better low-light performance. Their lack of moving parts also makes them lighter and cheaper. On the other hand, the range of focal lengths offered by a zoom lens can provide more flexibility, making them suitable for a wider range of subjects.

The choice between prime and zoom depends on your level of experience and the subjects you intend to photograph. If you are a beginner, a zoom lens can be a better choice as it will allow you to experiment with a range of focal lengths to find what you like. For more experienced photographers, the improved quality of a prime lens will usually more than make up for the reduced flexibility.

Aperture

A lens's aperture determines how much light it lets through. More often than not, a wider aperture (lower f-number) is preferable, as it will allow you to take photos indoors and in other situations with little or no natural light.

A wide aperture also allows you to use a faster shutter speed, which is important when photographing fast-moving subjects or when hand-holding the camera.

The down-side of having a wide aperture is the cost - lenses with wider apertures can cost significantly more than a normal lens. This is particularly true of long telephoto lenses, where an extra stop of aperture can easily double the price of the lens.

Focusing

Most modern camera lenses have a built-in autofocus mechanism which takes the guesswork out of getting sharp photos. Some specialist lenses may use a manual focusing system, so be sure to check this out before buying.

Some lenses employ more advanced focusing systems to meet particular needs. Silent autofocus is useful for macro and candid photography, where the lens sound can alert the subject and potentially ruin your shot. Internal focusing means that the outside of the lens stays perfectly still, which can be beneficial in macro photography where any movement could scare your subject away.

Image Stabilisation

When photographing at slow shutter speeds, camera movement can cause blurring in your photo. Image stabilisation (IS) is designed to reduce this, making your shots sharper and allowing you to shoot at slower speeds without using a tripod. Optical image stabilisation is considered superior to digital image stabilisation, although it does cost more.

A lens with image stabilisation will typically give you an extra 2 to 4 stops of exposure, allowing for exposures 4 to 16 times longer without a noticeable increase in blurring. This can be very useful when shooting in low light, or when hand-holding a telephoto lens.

Lens Fit

All lenses attach to the camera using some sort of locking lens mount. These come in bayonet, screw-thread, and friction-lock varieties, and they act to attach the lens to the camera body and join any electrical connections.

Each camera manufacturer has its own design, and while they often look very similar, they are not interchangeable. When shopping for a camera lens be sure it has the proper fit so that it will mount on your camera. Most third-party lens manufacturers sell the same lens with different mounts to cater for this.

Size and Weight

You should choose your lenses based on the subjects and situations you intend to photograph rather than the lens's size and weight, but these can be important as a final consideration.

The most important factor is the lens's focal length - longer lenses tend to be bigger and heavier. Aperture also plays a small role in the lens's weight, with a wider aperture requiring a more complex, heavier internal construction. Any extra features such as silent focusing or internal focusing will also generally increase the weight, especially for longer lenses.

If you intend to shoot hand-held, a lighter lens is better as it will be easier to move around and won't ache your arms when used for extended periods. Heavier lenses are sometimes necessary, and you should support them properly using a tripod or monopod. However, be aware that this will reduce your mobility.

The size of a camera lens can be important if you need to carry it in a travel bag or pack it to take on a plane, where space is limited. For these purposes, some manufacturers make lenses which are lighter and more compact than their counterparts, but this will increase the cost.

Buying a Camera Lens

Begin by listing the types of subject you intend to photograph. This may be a single type, such as "portraits", or it may be several, such as "portraits and close sports". Use the table above to select a suitable range of focal lengths to shop for. If your subjects are too far apart (e.g. "interiors and wildlife"), you probably won't find a single lens to cover them all.

Next, consider the likely lighting conditions you will experience. Be sure to consider the worst case scenario so that you can choose a lens that will cover all situations. If you will be using your lens in low light then a wide maximum aperture is essential - you should aim for at least f2.8 for well-lit indoor shots, and at least f1.8 for darker interiors. If you will mostly be using your lens outdoors in daylight then a wide aperture isn't quite so important, but is still preferable.

If there are any special features you require, such as silent autofocus, then list these too. Try not to add these extras just for the sake of it, as they can push the price up quite significantly, and aren't worth it if you won't use them.

Once you have your lens spec mapped out, you can begin looking for specific models. Online stores like Amazon and Adorama are a good place to start, and you can get opinions on particular lenses by visiting review sites and forums.

With some research you should be able to narrow your selection to a handful of suitable products. In general, if you own a Canon or Nikon camera, the best lenses are the ones made by those manufacturers, but there are also some excellent third-party brands such as Tamron, Sigma, and Tokina, which tend to be cheaper.

If you can't find a suitable lens that's within your budget then resist the temptation to buy something cheaper but which doesn't quite do what you want it to do. Camera lenses tend to last for years, so it's usually better to wait and save money until you can afford the one you really want.