1. If you want crisp, dramatic images there is no substitute for ‘fast glass’. For this reason, spend money on a good lens first and a camera second. You are going to get a much better result using a R2000 camera with a R10 000 lens than the other way round. Lenses date far more slowly than cameras do – and don’t be afraid to buy them second hand.
2. When buying a lens, the rule of thumb is to look for the widest aperture that you can afford. This corresponds to the smallest f-stop (in the case of professional lenses this is usually f2 8 or f4). The wider the aperture, the more light can be ‘sucked’ into the lens and the better the result in low light conditions. A fast lens allows you to make use of faster shutter speeds and, when you’re shooting at wide apertures such as f2 8, to blur out the background and create more foreground interest.
3. For general wildlife photography you will need a 200mm or 300mm lens or, better still, a 400mm. If you intend concentrating on birds, you should seriously consider going for a 500 mm or 600mm lens. A professional zoom lens will operate at the same f-stop (f4 or f2.8) throughout the range of the zoom, whereas a smaller, cheaper lens may start at a relatively decent f5.6 at 70mm, but decrease to f11at 300mm and this can render the speed of shooting and the quality of the image almost unusable. The difference between the 300mm lens that can fit into your pocket and costs a few hundred rand and the 300mm torpedo that is the same price as a small car boils down to the size of the bit of glass at the front of the lens.
4. Image stabilization, which allows shutter speeds 2 to 4 stops lower (or exposures 4-16 times longer) , than traditional lenses is a real asset for wildlife photography. These days autofocus is old hat, but the best zoom lenses have a motor built into the lens that allows focus with blistering speed.
5. Tele-converters can magnify your lens power by factors of 2, 1,4, or 1,7. A word of warning: a 2x converter will cut out two f-stops turning an f2.8 300mm lens into a f5.6 600mm lens. If you have a lens which offers 300mm at f8 you will get 600mm at f16 which is virtually unusable.
6. A mid-range zoom, of say 70 – 200 mm is ideal for portraiture and also for general photography. It is also ideal for shooting from game drive vehicles when animals are relatively close to the vehicle.
7. Standard lenses for full frame cameras are usually in the range from 24 – 70mm when using. For cameras with a cropping factor you will get the same effect from a lens with a wider frame of view such as 18 – 55mm.
8. You will also need a wide-angle lens. For full frame cameras a 20 mm lens is usually sufficient; for cameras with a cropping factor you will get the same result from a 12 or 14 mm lens.
9. Macro lenses allow close focusing and also give you a great deal of creative opportunities with smaller subjects. They are typically 1:1 which means that the size of the image on the sensor is the same size as the subject that you are photographing. But they are also defined by their ability to focus from very close distances. 100mm is perfect for a full frame camera. If you have a crop factor you may want to go for a 60mm. 180mm macro cameras can give you a closer view and very dramatic results but are also quite tricky to use.
10. The Japanese term bokeh is used to describe the background of an image. Most photographers would like the background when using a telephoto or macro lens to appear indistinct so that the main subject stands out as much as possible. With a lens that provides poor bokeh this will not be possible
If you have any questions about buying wildlife lenses please post them here and I will try to get back to you with a suitable answer. Or other readers will do so