Outdoor Photography. Chiz Dakin
Чтение книги онлайн.
Читать онлайн книгу Outdoor Photography - Chiz Dakin страница 11
Название: Outdoor Photography
Автор: Chiz Dakin
Издательство: Ingram
Жанр: Спорт, фитнес
isbn: 9781849658690
isbn:
Where it gets really confusing is with other SLR formats, such as the widely-used APS-C. This is just under half the size of 35mm/full-frame and therefore, naturally, gives less picture coverage, or angle of view, from any given lens. The same lens on a Nikon D700 (full-frame) and D7000 (APS-C) will give different results; an 18mm lens on the APS-size camera gives coverage equivalent to 27mm on full-frame (see photos). 18mm is commonly found as the wide end of DSLR kit lenses. On an APS-C camera this is 27mm-equivalent, so it gives a slightly less wide view than the 24mm-equivalent found on a few compacts – but on the SLR you can always fit a wider lens. On the compact you’re stuck with what you’ve got.
HANDLING THE CAMERA
Cameras which rely on screen viewing produce a distinctive ‘praying mantis’ posture. Some of these cameras are so small that it’s hard to get a decent two-handed grip, but two hands will always give better support than one.
Good handling, with the left hand supporting the lens. On a very wet day, the camera is in an Aquapac waterproof case. (Jon)
SLRs in particular are designed for shooting with the viewfinder. This gives an extra point of contact – the photographer’s head – and is therefore intrinsically more stable anyway. To get the very best support and access to camera controls, make sure the left hand is cupped underneath the lens, with the thumb and index finger forward.
This is really the best way to hand hold any camera, as long as the lens is large enough to allow it. The ergonomic advantages become even clearer when longer lenses are in play.
In this book, when we refer to focal lengths in the general text you can assume it’s ‘35mm equivalent’ unless we specifically say otherwise. So if we say 28mm we mean a moderate wide-angle and if we say 14mm we mean a pretty extreme wide-angle. To get a better idea of what this really means, take a look at the daffodil image opposite. This was taken on a full-frame DSLR, so the 12mm lens really is a 12mm (35mm equivalent).
Lens Types
Most lenses that you can buy, and nearly all those that are sold as a kit with a camera, are zoom lenses. ‘Zoom’ means that the lens has a variable focal length. A typical kit lens might be 18–50mm, 18–70mm or even 18–105mm: 18–50 is about a 3x zoom range, 18–105 is about 6x. This is a pretty decent range, which covers many needs, but the interchangeability of SLR lenses gives you a much wider range of options.
While zooms dominate the market, there are still many lenses with fixed focal length, also known as prime lenses, from 14mm wide-angles to 600mm and 800mm telephoto monsters. Prime lenses are simpler to design and build, and can be light and compact, and some critical users still reckon they give better optical quality. However, it can’t be denied they are less versatile than zooms.
Daffodils beside Ullswater, Lake District (Jon) A real wide-angle lens (12mm here) can take in both foreground detail and the sweep of a landscape
Near Garstang, Lancashire (Jon) Showing the coverage given by the same lens (48mm) on full-frame and APS-C cameras. The APS-C frame is indicated by the red line
Apart from focal length, lenses also vary in their maximum aperture. Wide maximum apertures have several advantages: they give a brighter viewfinder image, give extra options for shooting in low light, and allow you to achieve narrower depth of field. On the other hand, they make lenses bigger, heavier and more expensive. f/2.8 is a wide maximum aperture for a zoom lens, especially if it is maintained throughout the zoom range, but some prime lenses go as wide as f/1.4. Lenses with a wide maximum aperture are sometimes called ‘fast’ lenses but this is so fraught with potential confusion that we won’t use the term. Just watch out if you see a lens described this way: it doesn’t necessarily mean – as you might think – that it has a fast focusing action.
Franco, Cuesta del Viento, Argentina (Chiz) A long lens (400m here) allows the photographer to fill the frame – and the subject’s hair gives a clue how windy it is!
The vast majority of lenses sold today are autofocus lenses. Most can also be switched over to focusing manually, and it is occasionally advantageous or even necessary to do so. Lenses with a very wide zoom range are sometimes referred to as superzooms. There’s no clear definition of what constitutes a superzoom. The widest range currently available in a single lens is 18–270mm, or 15x. This is impressive but of course there are drawbacks. Superzooms may deliver decent optical quality in mid-range but are often less impressive at the extremes – and the extremes are the reason for buying a superzoom. A particular problem is distortion (straight lines appear curved). This might appear to be more of a problem for the urban photographer than the outdoor type, but can you honestly say you never photograph anything with straight lines in?
Some cameras claim extraordinary zoom ranges thanks to ‘digital zoom’. This is a highly misleading name for what should be called ‘in-camera cropping’. As you can always crop digital pictures afterwards, digital zoom is not worth an extra penny. When comparing cameras, look at the ‘optical zoom’ range.
Specialist lenses
As well as the regular zoom and prime lenses, there are various specialised types of lens. Mostly we’ll mention these in specific chapters where they may be relevant, like macro lenses for close-up work). Other types you might encounter include:
Fish-eye lenses: ultra-wide-angle lenses where distortion is allowed to run wild giving a uniquely curved view of the world.
Perspective control/Tilt and Shift lenses: lenses with a range of movements built in, allowing correction of perspective (like converging verticals when looking up at tall buildings), and very precise control over depth of field.
Sunflowers, Beaujolais, France (Chiz) Wide maximum apertures (here f/5.6 at 400mm) allow you narrower depth of field
Image stabilisation
It’s hard to know whether to deal with this under lenses or under cameras. This is a range of technologies designed to compensate for the effects of camera shake, allowing you to get sharp images at slower shutter speeds than would be possible without it. With compacts and ultra-zoom cameras it is naturally built-in to the camera but some SLR makers – notably Nikon and Canon – build this technology into the lens instead. This has the obvious advantage that you can retro-fit a stabilised lens to an older camera. This technology goes by many names: image stabilisation, vibration reduction, vibration control, SteadyShot, and so on.
It’s generally a good thing, but (there are always buts!) it has limits. You still can’t hand hold the camera and get a sharp picture at, say, 1 second shutter speed. Also, stabilisation only compensates for camera movement. It can’t do anything about blur caused by a moving subject. It certainly does not mean you can entirely forget about shutter speed. If you are using a stable tripod, it’s best switched off – or it will try and compensate for movement that isn’t there, and may actually introduce some camera shake!
СКАЧАТЬ