Choosing the right DSLR lens
For cameras with removable optics — i.e. SLR, medium-and large — there are a number of lenses to choose from. But common to most is that different manufacturers have their own connection — so you normally cannot use a lens from another supplier unless it is made for your camera brand.
Normal Lens
A normal lens has a focal length of 50 or 55mm. The reason for the name is that the point of view here is the same as for the human eye. This is a lens that covers a great many situations, and are often both affordable and has good optical quality. Most also have very good lighting — something that is useful in dim lighting.Wide Angle Lens
A Wide-angle lens is a lens with short focal lengths and therefore a large viewing angle. All focal lengths that are smaller than normal are called wide-angle lenses. Wide-angle lenses are often used for landscape images and architecture. A moderate wide angle (about 35mm for the small-screen format) is the most classic article lens.Extreme wide angles with a viewing angle of approximately 220 degrees and uncorrected so-called thin-shaped distortion is called fish-eye lenses, or more frequently Fisheye. An extremely wide-angle can be assembled by of up to 11 lens elements. These lenses were first constructed for sky observations, but has since found other users. Fisheye effect can be achieved in the mirroring of a Christmas tree ball, wheel capsule or similar that is photographed.
The optical aberrations increase when the light from the subject falls outside the lens center axis. It goes without saying that the light 90 degrees from center axis can only illuminate half of the front lens, but we can still see a picture. An extremely wide-angle lens can in principle look a little backward. The chromatic and spherical errors that occur here are not easily corrected. It is not easy to provide a wide-angle lens with a filter. The image is usually vignetted because the light has a tendency to polarize in the filter. The industry tends to provide extreme wide angles with selectable filters in the optical path. It is usually red, yellow, UV, and skylight filter.
Short Telephoto Lens
Lenses with focal length from 70 - 135mm, we refer to often as a short telephoto lens. These lenses are suitable both to the landscape, portrait and close photography. Between 80 - 105mm is often used in portrait photography.With this focal lengths, we get little depth by using the largest aperture — which is ideal at portrait and close-up photography, it is then desirable to get a sharp focus in a particular area and have a diffuse background.
Long Telephoto Lens
Lenses with focal length in the range of 135mm to 300mm is often called long telephoto lenses. These are often used for nature or sports photography. When using these lenses, you should usually use a tripod to avoid motion blur. Many of the lenses from the range of approximately 200mm and above have specialized mounts for tripods.The angle of these lenses goes from 18° to 8°. This makes them very well suited when we want to isolate something in a crowd, without getting too much of the environment in the picture. In contrast to the wide-angle lenses, telephoto lenses compresses the picture so that the distances seem smaller than they really are. Depth sharpness is relatively small, and we must the aperture well down to get both the foreground and background sharp. If we want to have good lighting on these lenses, they are both large and very expensive.
Extreme Telephoto Lens
Focal length of 300mm and above is considered extreme telephoto lenses, and are used essentially by nature and sports photographers. These lenses are very heavy and requires powerful tripods during use.Macro Lens
A macro lens is a telephoto lens that can focus very close to your subject, and as a rule, they can render the subject in the ratio 1:1 — that is the size of the motif in the film become equal to the real size.With such lenses you can focus down to a distance of 10-15cm from the lens to the object. On such short distances the depth of sharpness only 2-3 mm, and you must be careful with the settings of the camera/focusing.
Zoom Lens
In a zoom lens, we can change the focal length by adjusting the lens. This makes it possible to adjust the view without moving. These lenses have such optical quality, that they normally are more than good enough for normal photography.The lenses are available in a variety of ranges, from wide-angle to telephoto. There are also some that extends from 28mm to 200/300mm. This is usually straightforward, all-round lenses, and can safely be used for travel/holiday use. If you on the other hand, is depended on an objective that offers "extremely" good results, you should not choose lenses with such large advances in focal length.
Some of the most common variations are:
17-35mm — 28-70mm — 35-70mm — 28-105mm — 70-200mm — 70-300mm — 80-200mm
