Choosing A Lens (The Eye Of Your Camera!)

Lenses that are included with entry-evel and mid-range camera bodies tend to be lower quality, made from cheaper materials and with limited aperture ranges. Instead, get the very best you can afford, and you will reap the rewards with superior image quality.

Naturally, people want a single lens that can do everything, and for a low price, but as with most things, there are compromises to be made. Some of the things to consider before buying a lens include:

Focal length

The focal length of a lens refers to the magnification of a scene that it provides. Wide angle lenses, such as an 18mm or 24mm lens, enable you to fit more of a scene in and are best for group portraits. However, if you want to fill the frame the face of a single subject, then you’d need to move in very close to him or her. Not only could this feel intimidating, it will also result in distorted portraits with exaggerated foreshortening, giving your subject a huge nose and tiny ears.

Telephoto lenses, such as an 85mm or 200mm lens, have a much narrower angle of view, and enable you to crop in close to one part of a scene or subject. However, you need to move further away from your subject in order to include more of their body in the shot. This can make it harder to interact, and can be impossible in a small room. Longer focal lengths can also flatten perspective, making the background look much closer to the subject than it really is – something that you can often use to your advantage, but need to be aware of. This lens type produces much more flattering shots than wide angle lenses, and can feel less intimidating as they are used further away from the subject.

Whether you choose a wide angle or a telephoto lens, bear in mind that unless you have a camera with a full frame sensor, the actual focal length will be more magnified, as smaller sensors ‘crop’ into the image. This means that a 50mm lens would have an effective focal length of 75mm-80mm on a camera with an APS-C sensor.

As a minimum, professional photographers would typically have a 24-70mm lens for wider angle work and a 70-200mm lens for close-up work. Wedding photographers may also have a 16-35mm, in order to include more of the venue in shots, and for group portraits, and possibly a ‘fast’ prime lens too.

Maximum aperture

Wide apertures enable you to isolate the subject by blurring the foreground and background. They also allow more light through the lens, which means you can work in lower light conditions and achieve higher shutter speeds (minimising camera shake). For this reason, lenses that offer extremely wide apertures are referred to as ‘fast lenses’.

Professional portrait photographers often take the vast majority of shots at the widest end of the aperture scale, f/1.8, f/2.8 and f/4, for example. Yet many kit or entry-level lenses may only offer f/3.5-5.6, which really limits your options.

Look for a good quality prime lens which opens up to f/1.8, or a zoom lens that offers a fast, constant aperture throughout the focal range.

Zoom Vs Prime Lenses

Zoom lenses offer a range of focal lengths, which means you can crop into and out of a scene without physically moving yourself nearer or further away, by simply rotating the lens barrel. Optically zooming in this way provides superior image quality compared to taking a wide angle shot and cropping it digitally, as the latter method simply results in the selected area of pixels being magnified. However, make sure you check the maximum aperture throughout the focal range of a zoom lens, as cheaper models can’t achieve the widest aperture at every setting. Having wide apertures at all focal lengths adds greatly to the cost of the lens, as the design is more complicated and more optics are involved.

Prime lenses have fixed focal lengths, which makes them cheaper to design and manufacture, as the optics only need to be optimised for a single level of lens magnification. If you’re on a budget, you’ll get better quality from a prime lens than a zoom lens at a much higher price point. However, you’ll need to work harder, moving yourself or your subject in order to achieve different crops. 50mm, 70mm, 85mm and 105mm prime lenses are ideal for portraits, as they avoid the distortion of wide angle lenses but don’t require vast amounts of space between you and your subject in order to fit them in the frame. You can get very good 50mm f/1.8 primes from the main camera system brands for around £100, which is significantly cheaper than a good quality zoom lens.

Build quality

The more you spend, the better the aperture and focal length range available to you. However, there are additional benefits to higher-end lenses, including improved weather resistance, better build quality and faster, more accurate focusing, especially in darker scenes. The out of focus rendering of points of light in shots taken with wide apertures – known as bokeh – is also more aesthetically pleasing in images captured with a better quality of lens.

Filters

Having splashed out on a high quality lens, you can increase its longevity by adding a filter, which helps to protect it. The most common filter types screw into the end of the lens. Filters can add effects, such as neutral density filters which darken skies, UV filters which reduce haze in landscapes and polarising filters which minimise reflections and increase the intensity of blue skies. For most portrait work, however, a Natural Colour filter is best, as it won’t add any additional effects. Remember that your shots will only be as good as the glass you use, so spend a little more to get a decent filter.