Canon EOS Digital SLR Product Range - Eos40D, Eos400D

Have you noticed how much the choice of a lens can affect the photographs you take? Different lens focal lengths can radically change the way you look at a subject - and the reactions you elicit from people when they look at your pictures. Although most cameras come with zoom lenses, the range of focal lengths covered by a typical zoom lens is relatively small. Additional lenses can help you to expand your photographic point of view.

In theory a lens that's equivalent to a 50mm focal length on a 35mm camera gives a 'normal' viewpoint in which the subject's proportions are rendered in much the same way as the human eye sees them. Shift to a wide angle lens and that perspective changes. Wide angle lenses cover a wider field-of-view and include more of the subject. You need to move in closer to make the subject fill the field of view and, with more extreme wide angle lenses, this can introduce some interesting distortions. From a viewer's perspective, wide angle lenses create an 'inclusive' feel to a picture because they draw you into the picture.

See what the difference a different focal length can make! The ginger cat was photographed with an extreme wide angle lens. Note the distortion and how sharp the image is from the cat's front paws to its back legs. The grey cat was photographed with a long telephoto lens. See how easy it is to blur the background and make the cat's face stand out.

On the other hand, telephoto lenses tend to isolate the subject, enlarging it and making the viewer concentrate on a small field-of-view. The longer the tele lens focal length, the greater the sense of isolation it creates. Tele lenses also tend to compress perspective, making objects in the picture that may be widely-spaced seem to crowd in on each other. They can also produce a more flattering perspective for portrait shots.

All these factors can help you to make more interesting pictures - even of fairly routine subjects.

The subject will influence the effect you obtain. For landscape shots where you want to include as much of the scene as possible, the primary decision you must make is where to place the horizon. If the sky is more interesting than the foreground, make it the focus of the shot and place the horizon low. If the foreground is more interesting and the sky is cloudless blue or overcast grey, positioning the horizon towards the top of the frame will create a more interesting picture. Avoid shooting with the horizon across the middle of the frame; you need an exceptional subject to make an interesting picture when the frame is split symmetrically. If your camera has on-demand grid lines they can be used to ensure the horizon is level.
Moving in on a subject with a wide angle lens can create some interesting distortions - and the wider the lens, the closer you can shoot and the greater the distortion effect. You can take some amazing shots in this way, although children and pets may feel uncomfortable when a camera is close to their faces so you will need to work quickly. Find out just how closely the lens focuses so you know how close you can come before starting to take pictures.

Mounting your camera on a tripod can make it easier to take a sharp picture, although it may also limit your scope for trying out different shooting angles. Most compact digicams have their closest focusing points at the wide lens setting. However, if you would like some more 'working room' between the end of your camera's lens and the subject - for example, when taking pictures of insects - you can easily set the lens to 'tele' and shoot from further away. With a digital SLR, best results are usually obtained with a moderate telephoto setting, although, if you have a special macro lens it will do an even better job than a zoom lens.

Wide angle lenses are great for landscape photography because they allow you to produce 'immersive' pictures.

Decide which part of the subject you want to capture and select an appropriate zoom setting. For portraits, a focal length equivalent to between 85mm and 135mm on a 35mm camera will reliably produce attractive results. Use a relatively wide lens aperture - say, f/4 or f/5.6 to blur background detail and concentrate the viewer's eye on the main subject. Take at least four shots in quick succession to ensure you have at least one picture where the subject hasn't blinked as the shutter opened. Keep the ISO set on auto or at 100 or 200 to ensure high image quality.
For sports action and shots of wildlife you will probably need the longest focal length available - and it will be helpful to have image stabilisation, either in the camera or the lens. Boost the camera's ISO setting to 400 (or higher is the light is dim) so you can shoot with fast shutter speeds. If in doubt, select the Sports mode as it will engage fast shutter speeds and high sensitivity settings. Using a lens with image stabilisation will help you to capture sharp pictures.
Watch out for camera shake. In dim lighting, track the subject with your camera and slowly press the shutter button when you have the subject in your sights. Don't jerk the camera as that will blur the shot. The shutter mechanism will set the correct exposure time and, as long as you are moving the camera in synch with the subject, the shot should be sharp.

A long telephoto lens will allow you to take great close-ups of tiny birds and animals in the wild. Image stabilisation is essential if you want to obtain sharp pictures. For larger birds and animals - especially those which are relatively tame - a medium telephoto lens will do and image stabilisation may not be required. Not the difference in background blurring between these two telephoto shots.