Digital SLR Handbook. John Freeman
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tips
• Taking good care of your camera and lenses will help ensure that they perform as they should at all times.
• Shield your camera and lens from draughts or wind when changing optics.
• Never use pressurized (canned) air to remove dust from inside the camera.
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Lenses
The DSLR system comes with the widest range of different lenses available to cameras. Even medium-format cameras, such as Hasselblads, and large-format models and rangefinder types, such as Leicas, have far fewer compatible lenses.
Range of lenses
Not only are DSLR lenses available in different focal lengths, from fisheye to ultra telephoto, but there are also many specialist lenses, such as shift and tilt lenses and macro lenses. (see the following pages for pictures of the most usual lenses and the types of image that they produce.) In addition to the lenses made by the camera manufacturers, there are many independent lens producers who supply competitively priced alternatives.
With such an array, you might feel daunted trying to select suitable lenses. What’s important is that you buy the best in their field – there is no substitute for high-precision optics. If that seems extravagant, remember that your lenses will outlast your camera by years, provided they are treated with care.
Buying lenses
When I buy a lens, it is because I need it for a specific purpose and because I know I will get the maximum use out of it. Although it might be desirable to have a 600mm telephoto lens in my kit, the financial outlay can’t be justified – lenses such as this cost thousands – unless I am going to do a lot of wildlife or sports photography, for example. If I intended to use it only occasionally, I would consider hiring one from a professional photographic dealer instead.
50mm focal length lenses, when used with the 35mm format, have roughly the same field of view as the human eye, which makes them perfect for recording images in much the same way as when we first see them, with little distortion or compression.
> Canon EOS 1DS, 50mm lens, 1/125 sec, f/8.
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Wide-angle lenses, such as 24mm, are perfect for shooting expansive landscapes. However, it is all too easy to include great swathes of uninteresting foreground detail and bland skies. In this shot, the road and cloud detail add to the composition.
> Canon EOS 1DS, 24mm lens, 1/400 sec, f/11.
Three lenses form the cornerstone of my kit: 16–35mm, 24–70mm and 70–200mm. With these I have wide-angle, normal and telephoto capabilities that cover most shooting situations. They all have a maximum wide aperture of f/2.8 throughout their range (see below), and their quality is superb. As I shoot a lot of architecture, I have a range of shift and tilt lenses, which are invaluable for correcting converging verticals. I also have a fisheye, which is particularly useful when shooting interiors of large buildings, such as churches. A macro lens completes the kit. I use this for close-up work, chiefly nature subjects.
Apertures
All lenses have a maximum aperture, such as f/1.4, f/2.8 or f/5.6. Lenses with a maximum wide aperture of f/1.4 are sometimes referred to as ‘faster’ than a lens of the same focal length whose maximum aperture is f/5.6. The quality of a fast lens is far superior to that of a slower one.
The maximum aperture on a zoom lens can vary. For instance, a 70–200mm lens might have a maximum aperture of f/3.5 when it’s set at 70mm but the maximum aperture might be only f/5.6 when set at 200mm. This loss of speed might create problems if you’re shooting in low light. In my experience, a zoom lens with a variable aperture will not have the resolving power and sharpness of a lens with a constant aperture throughout its focal length range, such as f/2.8. However, you might end up paying up to four times more for this superiority in a lens. Wider-angle lenses, due to their inherent characteristics, have greater maximum apertures than telephotos, such as f/2.8, while a superior 600mm telephoto might have a maximum aperture of only f/4. However, for a 600mm lens this is extremely fast.
Telephoto lenses are great for bringing distant subjects closer. This is essential in wildlife photography, where being near to the subject would probably scare it away.
> Canon EOS 1DS MK2, 200mm lens, 1/500 sec, f/2.8.
Zoom lenses are a great way of reducing the amount of kit that you need to carry. Three zoom lenses, such as a 16–35mm, 24–70mm and 70–200mm, should cover virtually all normal situations. They are also excellent for creating in-camera effects, such as in the shot on the right.
> Canon EOS 1DS MK2, 28–200mm f/3.5–5.6 zoom lens, 1/15 sec, f/16.
Although fisheye lenses have limited uses, they can create unusual, eye-catching shots, often giving a different outlook on familiar views, such as this cityscape of Florence. The 180° view of a fisheye means that you need to be extra careful about what you include in the frame.
> Canon EOS 1DS, 15mm f/2.8 fisheye lens, 1/250 sec, f/8.
Sensor size
At the top end of the DSLR range, most lenses have sensors equivalent in size to the old 35mm film format (i.e. 24 × 36mm), which means that they are compatible to the focal lengths attributed to them. However, many DSLRs come with a sensor that is too small to capture the same image possible with a film camera. This is not so much of a problem when taking portraits or if you require maximum telephoto capabilities, but it can be a problem with wide-angle lenses. A 28mm lens on a DSLR with a sensor of only 23 × 15mm, for example, will result in the lens having an equivalent focal length of only 44mm. This is hardly wide angle and makes the lens not worth buying.
Manufacturers are now addressing this problem by producing ever wider lenses – whereas 17mm would have been thought of as extreme only a few years ago, it is now possible to buy a wide-angle lens with a focal length of only 10mm for a DSLR camera.
Macro lenses enable you to get close to nature – magnification up to life size (1:1) is possible – and are excellent for photographing plants and flowers. Working distances can be problematic in certain situations due to the proximity of the lens to the subject.
> Canon EOS 1DS, 100mm f/2.8 macro lens, 1/85 sec, f/5.6.
Shift and tilt lenses are one of the many specialist lenses available to the DSLR camera user. They are especially suited to architectural photography, as they eliminate the problem known as converging verticals, where buildings appear to taper towards the top.
> Canon EOS 1DS, 24mm f/3.5 TS-E lens, 1/400 sec, f/11.
Ghosting