Types of lenses
First, let’s define what kind of lenses are generally.
All lenses are traditionally divided into wide angle, normal or normal, and telephoto. As we know from the lessons of geometry, the angle of view depends on the ratio of the focal length (FR) to the diagonal matrix, or film, but along with this, the prevalent film format “35mm” is considered to be the lens not the angle, and the so-called “equivalent focal length” (EGF). “Normal” lenses have camera of about 50mm, a wide angle 28-35mm, but more is called extra short throw. Longer lenses tend to have EGF 100-400mm. We should also mention the EGF 80-100mm – often referred to as “portretiki”. Therefore, with these lenses the face of a man close-up has the most natural perspective, or rather, they provide a more natural perspective. By themselves, of course, lenses for the future does not affect. Digital matrix diagonal are smaller than the film, with the goal of providing the same angle of view, make the image proportionally smaller. Thus, with a matrix diagonal 9mm (so-called 1/1,8″ matrix), the normal lens will be 10 mm, portretiem will be 16-20mm, and 35mm still full “telephoto”. Thus, the characteristics of all we can observe various FR 2 – true and equivalent. For example, it is quite common zoom along with DF=7-21mm and EFR=35-105mm.
On the rim writing by the fraction value FR and the aperture, for example 50/1,4 or 7-21/2,0-2,8. In the latter case, the inscription means that intensity at 7 mm equal to 2.0, and at 21 mm to 2.8. Very often the aperture value do not write the number (particularly 8), and with the letter F (for example F/8). In addition, the technical characteristics of commonly in addition to the write intensity and the range of diafragmirovanija, for example, in digital cameras it’s F/2-F/8. The result is often in the reviews, especially the comparative range of the aperture value confuse or together with a range of intensity, or even with focal length (because of the letter F). These “typos” can be damaged during the comparative range of cameras.
Just in case again, that intensity is the maximum open aperture. So if it says that the lens 7-21 mm/2.0-2.8 aperture from 2.0-8.0, it means that now, with 7 mm aperture range 2-8 (and also aperture = 2,0), but 21 mm range of 2.8-8 (and also aperture = 2.8 m).
Back to the angles. To many Amateur shooting for a “normal” lens is (EGF=50 mm), because his coverage of the space close to the natural perception of the eye. Of course, sometimes I want to fit into the frame more (a landscape, a close place), but sometimes on the contrary to shoot something closer close-up (portrait or detail, in case of impossibility to run up for a few seconds to the subject). Therefore, commonly known as the primary, and in some models, and a single lens, apply zoom along with a range of “about” normal, particularly with EGF 35-90 or 35-105. The ratio of “long” how to “short” is called the zoom ratio, measured in letters “x” and is often indicated on the body, especially among film cameras with long “trunks”. Most believe that the more the value of “x”, the better. But if you’re going to take something special (extremely large landscapes, for example, Safari), it’s worth thinking about replacement wide-angle/telephoto. Supermultiple zoom, no doubt, partially rescued the situation, at the expense of price or quality, or intensity. There are also “attachments” on a regular lens, but any specialized “shirik”/”telephoto”/”mikrik” takes noticeably better than universal zoom along with accessories.
Fixed lenses are almost always superior to zoom lenses according to image quality (unless, of course, does not compare very affordable mobile with very expensive zoom). In addition, high aperture optics with variable focal lengths isn’t cheap, but the cheap range of fast fixes there is each manufacturer.
The fixes are not so easy to use, so as to respond to various challenges, you need a huge number of lenses. Change them when the dynamic change of the shooting conditions is difficult and takes a lot of time. To give preference to fixed-lens to if the speed while changing focal lengths for you is not the most important criterion.
If you enjoy taking pictures of plants, insects and other small objects, in this case, you will need a macro lens. Maximum magnification and minimum focusing distance, the lens forms an image that almost fit to the real conditions.
Cheap macro lens with a focal length of 50 and 100 mm very compact, and only for shooting at maximum zoom you need to remove them, fully leaning into the subject. It’s not very useful when photographing the same insect. With such a purpose requires a macro lens with an impressive focal length – 135, 180 mm. They provide the greatest multiplication, but are much more expensive.
Technical parameters of the lens
Lens selection is as important as choosing the camera itself, because it is a picture of the digital matrix or film. You have the opportunity to use only universal zoom lens for all occasions, but this perspective is not the best option. Remember, a good universal things anywhere else.
To determine what optics would suit you best, you should consider the following options:
focal length or range of lenses
fixed (fixed lens) or variable focal length (zoom lens)
manual or auto focus
the presence of image stabilizer
the macro capability
Focal length determines the angle of view covered by the lens, as well as transfer prospects. The smaller (shorter) focal length, the more the angle of view and more pronounced perspective. A lens with a focal length of 50 mm is considered normal for prospects, similar to the human eye. This lens is often used to create realistic-looking photos.
Lenses with focal lengths less than 50mm are considered wide angle (or short throw). They allow you to fit in the frame of a large area of space. Stretching the picture in the foreground, as well as on its edges, this lens has distorted the perspective. Most often they are used to shooting landscapes, architecture, as well as in close quarters.
You can select a class of extra-wide-angle – lenses “fisheye” (fisheye). These lenses typically have an angle of view of 180 degrees according to the diagonal of the frame. Because of the strong perspective distortion of such a lens forms a characteristic hemispherical image. The use of these unique properties of the fisheye allows to create wonderful images of architecture, landscapes and interiors, depictions of people.
Long-focus or telephoto lenses are used for photographing wildlife, sporting events, and also necessary in cases in which time plays a significant role, and you have no way to come close to the subject. A long range optics – portrait lenses. Due to the focal length from 80 up to 100 mm, they allow you to rediscover the natural proportions of the human face and blur the background with a minimum depth of display space.
Main lens focal length – distance from the main focus until the main back plane, indicated by the letter f.
The position of the main rear plane depends on the type of lens: normal lens it lies close to the aperture, at telephoto it is located in front of the lens, and only lens with extended main period behind them.
Focal length determines the image scale when setting the lens to infinity.
Is characterized by the minimum aperture setting, which allows you to install the lens. Lenses with larger aperture allow you to use faster shutter speeds. This means that now in low light you’ll get very sharp images. But along with the diaphragm reducing the number of falls the depth of the depicted space, which does not always match the intent of the photographer. In addition, the value of fast lenses is much higher.
Manual and auto focus
Almost all advanced lenses are able to traverse the sharpness automatically. But there are lenses and with manual focus, particularly old types, among which there are instances with very interesting characteristics. The optics of earlier generations is allowed to install a modern camera, using advanced adapters.
Recent good form from manufacturers of lenses and cameras is to set the image stabilizer. It allows taking pictures at slow shutter speeds with a small loss of sharpness. This is especially true for shooting with a telephoto lens in which to obtain sharp images requires very short exposure. Fashion optical stabilizer allows to multiply the exposure by 3-4 degrees. Some manufacturers have gone according to the way of embedding it in the lens, the other set in the camera stabilizer. The presence of the stabilizer in the camera allows shooting with long exposures of any lenses, which are installed on it. There are lenses, available in two versions – with stabilizer and without them. A version without stabilizer is typically jerky, and about one and a half times cheaper.
Compatibility of lenses and cameras