Under what circumstances is a wide-angle lens prone to distortion?

For example, when taking a group photo, the faces of people standing on both sides will be out of control.

The reason of distortion is that the lens has different bending ability to colored light, and the distance between the imaging point and the optical axis is different, and its lateral magnification is also different. Therefore, there is an abbreviation between the actual imaging and the ideal image. People can use Photoshop and other image drawing software to make simple modifications to make up for the deformation problem.

The focal length of a wide-angle lens is shorter than that of a standard lens, and the viewing angle is wider than that of a human eye. Generally, the wide-angle lens of a 35 mm camera has a focal length of 28 mm -35 mm and a viewing angle of 76-64 degrees.

Wide-angle lens has a large field of view and a long depth of field, which is used for general snapshot and general landscape photography. The focal length range is 15mm-24mm, and the viewing angle is 1 10 -84 degrees. It is a super wide-angle lens. Close to or even greater than 180 degrees are fisheye lenses.

Compared with the barrel deformation of wide-angle lens, telephoto lens or zoom lens may have pincushion distortion or pincushion distortion at the telephoto end, and the image of a square object will become concave at four sides and convex at four corners, like a pillow.

Zeiss16mm HOLOGON lens is an exception. It has a wide viewing angle of 1 10 degrees, but there is no distortion at all.

Extended data

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.