Key points of basic knowledge of wide-angle lens

Wide-angle lens is a photographic lens with shorter focal length, larger viewing angle, longer focal length and smaller viewing angle than standard lens.

Wide-angle digital camera has short focal length, wide viewing angle and deep scenery, which is suitable for taking photos of large scenes, such as architecture and scenery.

trait

The basic characteristics of a wide-angle lens are its large viewing angle and wide field of vision. The range of scenery observed from a certain viewpoint is much larger than that seen by human eyes at the same viewpoint; The depth of field is long, which can show a fairly clear range; It can emphasize the perspective effect of the picture, be good at exaggerating the foreground and express the sense of distance of the scene, which is conducive to enhancing the appeal of the picture.

fundamental characteristics

Wide viewing angle, covering a wide range of scenery. The so-called wide viewing angle range means that at the same viewing point (the distance from the subject is constant), the scene is viewed with wide-angle, standard and telephoto lenses with three different focal lengths. As a result, the former shoots more up, down, left and right scenes than the latter. When the photographer has no retreat, it is difficult to take a complete picture (such as taking a group photo) with a standard lens of 50 mm ), using a wide-angle lens can easily solve the problem. Furthermore, for example, shooting a vast Yuan Ye or a tall building in a city, perhaps only a part of the scenery can be photographed with a standard lens, which cannot show the breadth or height of the scenery. Shooting with a wide-angle lens can effectively show the open momentum of large scenes or majestic buildings. Short focal length and long depth of field. Photographers usually rely on the short focal length and long depth of field of wide-angle lenses to bring the whole scene from near to far into a clear range of expression when shooting a wide scene. In addition, when shooting with a wide-angle lens, if a smaller aperture is used at the same time, the depth of field of the scene will become longer. For example, if a photographer shoots with a 28 mm wide-angle lens, the focus is on a subject about 3 meters, and the aperture is adjusted to F8, then from 1 meter to infinity, it almost enters the depth of field. It is precisely because of this long depth of field that wide-angle lenses are often used by photographers as fast-moving lenses with strong maneuverability. On some occasions, the photographer can quickly capture the picture by manipulating the wide-angle lens without focusing on the subject.

You can emphasize the prospect and highlight the contrast between far and near. This is another important performance of wide-angle lens. The so-called emphasis on foreground and far-near contrast means that wide-angle lens can emphasize far-near contrast more than other lenses. In other words, the photos taken with wide-angle lens are closer and farther, which makes people feel that the distance has been widened and has a strong perspective effect in the depth direction. Especially when shooting with a super wide-angle lens with short focal length, the effect of being near big and far small is particularly remarkable.

Can be exaggerated and deformed. Generally speaking, it is taboo to use a wide-angle lens when the subject is exaggerated and deformed. In fact, it is not necessarily undesirable for the subject to exaggerate and deform appropriately. Experienced photographers often add content, use wide-angle lenses to moderately deform the subject, and take some very inconspicuous scenes that people turn a blind eye to. Of course, using a wide-angle lens to express exaggeration and distortion should be based on the needs of the subject matter, and the second should be few and precise. No matter whether the theme is necessary or not, it is not worthwhile to abuse the exaggerated deformation of wide-angle lens and blindly pursue the bizarre effect in form.

Shooting effect

Wide-angle lens is widely used to shoot large-scale landscape photography. Can increase the sense of spatial depth of the photo picture; The depth of field is long, which can ensure that the scene before and after the subject can be clearly reproduced on the screen. Therefore, the vast majority of modern pocket automatic cameras (commonly known as fool cameras) use ordinary wide-angle lenses of 38-35 mm; The lens covers a large area and shoots a wide range of scenery; The scene shot at the same shooting distance is smaller than the scene image shot with standard lens in the picture; The defects of perspective distortion and image distortion are easy to appear in the picture. The shorter the focal length of the lens and the closer the shooting distance, the more obvious this defect is.

For most popular digital cameras on the market, the wide-angle focal length is generally between 35 and 38 mm. The real wide-angle digital camera is actually a product with a lens focal length covering a wide angle of 28 mm

fish-eye lens

Take the interchangeable lens suitable for 35mm SLR camera as an example. Fish-eye lens is a kind of ultra-wide-angle photographic lens with short focal length, and its focal length is about 6- 16mm. "Fish-eye lens" is its common name. In order to make the lens reach the maximum photographic angle, the front lens of this kind of photographic lens protrudes to the front of the lens in a parabolic shape, which is quite similar to the fish's eyes, hence the name "fisheye lens". The biggest function of fisheye lens is its wide viewing angle, which can generally reach 220 or 230, creating conditions for shooting large-scale scenes at close range. The fisheye lens can produce a very strong perspective effect when shooting close to the subject, emphasizing the contrast between the near big and the far small of the subject, so that the shot picture has a shocking appeal; The fisheye lens has a large depth of field, which is beneficial to show the long depth of field effect of photos. There are two kinds of fisheye lens imaging, one is full of pictures like other lenses; The other imaging is circular. No matter what kind of imaging, the images taken with fisheye lens are quite deformed and have a strong sense of perspective convergence.

The size of fisheye lens is very large. Take the fisheye lens for a 35mm single lens reflex camera as an example. The fisheye lens is installed on the body of a smaller 35mm single-lens reflex camera, which has a feeling of "big head (lens) and small body (body)", and the weight of the fisheye lens is not light (for example, the manual focusing fisheye lens of Nicol 6mm /F2.8 weighs 5,200g). As mentioned above, the front lens of the fisheye lens has a large diameter and is thrown in front of the lens, so this lens cannot be equipped with a filter like a normal lens. Fisheye lenses usually use a built-in filter. According to the shooting needs, the photographer manipulates the filter conversion ring on the lens to convert the required filter into the shooting light path of the lens. The front lens of fisheye lens is a very important lens in the whole lens. Because it is thrown in front of the camera, the photographer should pay special attention not to collide with the camera when shooting (especially when shooting close to the subject). In addition, when some old fisheye lenses are connected to a 35mm single-lens reflex camera, the back of the lens is deeply inserted into the camera body, and the mirror of the camera must be turned up and locked, and the pentaprism viewfinder of the camera will not be used, so it is necessary to set an additional viewfinder on the camera to take pictures.

standard lens

Take the interchangeable lens suitable for 35mm SLR camera as an example. The standard lens usually refers to a photographic lens with a focal length of 40 to 55 mm, which is the most basic photographic lens of all lenses. The standard lens gives people a vivid visual effect picture, so it is often used in actual shooting. On the other hand, because the picture effect of standard lens is very similar to the visual effect of human eyes, the picture effect taken with standard lens is very ordinary, even very "plain", and it is difficult to obtain the dramatic effect of rendering the picture like wide-angle lens or telephoto lens. So it is not easy to take vivid photos with standard lenses. Even experienced photographers think it is not easy to use standard lenses well. However, the visual effect of the standard lens has a natural sense of closeness, and the distance between the standard lens and the subject is moderate, so it is widely used in ordinary scenes, ordinary portraits, snapshots and other photography occasions. The most common commemorative photos are taken with standard lenses. In addition, what photographers often overlook is that the standard lens is also a lens with good imaging quality, which is very effective for showing the details of the subject.

The odds are slim.

General characteristics

Take the interchangeable lens suitable for 35mm SLR camera as an example. A telephoto lens usually refers to a photographic lens with a focal length of about 80 to 400 mm.

The basic feature of telephoto lens is that the lens angle of view is small, so the field of view is relatively narrow; It can bring the distant scene closer and make it full of pictures, and has the function of "seeing far", thus making the sense of distance of the scene disappear; The depth of field is shortened, and the clear range of the subject before and after the focus is limited to a certain proportion to highlight the focused part (mostly the subject or the part that needs to be highlighted). Small viewing angle and narrow field of vision.

fundamental characteristics

Because of its small viewing angle and narrow field of view, telephoto lens only displays a small part or even a small part of the external scene usually observed by human eyes. Photographers may have this experience: installing a telephoto lens on the camera and observing it from the viewfinder of a single-lens reflex camera, they can't imagine where the scene filled in the viewfinder picture is at the moment, so they have to move their eyes away from the camera eyepiece to see the real scene, only to find that the field of view of the lens is too narrow, and it "sees" only a small part of the picture that the human eye usually sees, and the lens enlarges and fills the picture. Taking advantage of the small field of view of telephoto lens, photographers can describe the performance of the subject subtly when shooting close-ups of people, and highlight a beautiful part of the landscape when shooting landscapes. The telephoto lens has a small viewing angle and narrow field of view, which also makes the composition easy to gather scenery, so the picture is more compact. However, when the lens used has a long focal length and the object is in close focus, the focused object will be greatly enlarged, thus forming a strange effect.

Can make the front and back subjects feel oppressive. Another remarkable effect of telephoto lens is that it "zooms in" the distant subjects, thus making the front and rear subjects feel oppressive. In some major sports events, groups of photographers often set up cannon-like telephoto lenses to shoot the overlapping scenes of athletes at the start of the marathon. This is because on this occasion, the photographer can aim away from the subject by relying on the telephoto lens, which can "draw closer" the distant athletes, and at the same time bring the effect of compressing the foreground and background, showing an urgent atmosphere in which the subject is chasing after him.

Long focal length and short depth of field. Photographers can often see some photos with short depth of field. These photos have a sharp contrast between reality and reality, the main subject is clear, and the secondary subject is fuzzy, which has a strong artistic appeal. Most of these photos with short depth of field were taken with telephoto lenses. The telephoto lens has the characteristic of shortening the depth of field of the object. Especially when the telephoto lens is used with large aperture and short shooting distance, the effect of shortening the clear range of the subject is particularly obvious, and this technique is also often used to shoot subjects such as portraits.

Matters needing attention

1, the scene shot by wide-angle lens is near big and far small, and the perspective effect is exaggerated. The closer the subject is to the camera, the more obvious the exaggeration becomes. Therefore, when taking portraits, people should not be too close to the camera, otherwise it is easy to take deformed photos of "fat nose and mouse ears". Of course, the works of art shot with this effect are excluded, such as The Hand Holding the Vote, which is a very famous photo.

When shooting a building with a wide-angle lens, the lens tilts up or down, which makes it easy for the parallel lines of the building edge contour to shrink or intersect in the distance. Pay attention to choose the contraction point on the center line of the framing picture, otherwise it will easily skew the building image and give people the illusion of collapse.

2. When a wide-angle lens uses a hood or a color filter, it is easy to block the periphery of the lens viewing angle and darken the image field. This situation is not easy to detect when shooting, but it is obvious in the photo. Therefore, when using accessories, be sure to understand their scope of use from the instructions. If there is no explanation in the manual, you should be more careful when shooting.

3. The flash coverage angle of electronic flash is generally equivalent to the viewing angle of 35mm lens of 135 camera. Therefore, when taking flash photography with a wide-angle lens smaller than 35mm, a diffuser should be added in front of the flash window of the flash. If not, you can wrap a layer of white paper or white handkerchief to increase the flash area.

Coiling method

When buying a wide-angle digital camera, we should not only pay attention to the overall performance of the camera, but also pay attention to its lens performance. Lens distortion is the first factor we need to consider. Generally speaking, wide-angle shooting is more prone to distortion, but photos taken by different cameras have different degrees of distortion. Generally speaking, the less distortion, the better.

Secondly, pay attention to the resolution of the picture. Due to the limitation of cost, the lens quality of digital cameras is often inferior to that of professional SLR lenses, especially the edge resolution of photos may be significantly reduced, and a good wide-angle digital camera can be controlled relatively well and the picture looks clearer.

And anti-glare ability. Because the viewing angle is very large at a wide angle of 28mm, it is easy to encounter backlight or side backlight. If the camera lens has poor anti-glare ability, ugly spots will appear on the photo, and even light rush will appear. Of course, purple edge, dispersion and so on are also our key concerns.