Close to 10 cm objects, the human eye can not see. This means that humans cannot perceive more detail textures with their naked eyes. With the help of a magnifying glass, more detailed shapes can be observed. Micro-photography is an important and fascinating branch of photography, which uses a new perspective to observe the world. Textile texture, beetle wings, car logo, dew on petals. This is a mysterious and unique image world, which transcends the human eye's perception of details.
Today's photographers'knowledge of macrophotography is mostly acquired from dedicated macro lenses and a large number of online works. Close to the scene, fine focusing, and appropriate light supplement, the photos were born on the scaffolding in an attempt to be more stable. But the photo error rate often makes the photographer very angry, sometimes want to get a more microscopic scene but suffer from the common lens can only provide 1:1 magnification. To do better in macrophotography, we need to understand it from the whole situation.
Before talking about equipment, macrophotographers should know more about the words it emphasizes. They are in turn: magnification, nearest focusing distance, effective aperture and aberration.
Magnification rateMagnification rate
Magnification is the magnification factor. Usually, it refers to the ratio of the size of the final image to the size of the original object, which is the product of the magnification factor of the objective and the eyepiece after the object is magnified by the objective and then magnified by the eyepiece. The viewfinder magnification commonly used in photography refers to this point, which is expressed as a percentage. Macro-magnification has a new meaning, which refers to the ratio of image size to actual scene size on the focal plane. Focal plane or film or digital sensor CCD, CMOS. In micro-range, the image on focal plane is usually expressed as 1:* and 1:2 as half of the actual size of the object. The general definition of macrophotography is that it can achieve 1:1 magnification. Ultra-macrophotography generally means that the image is larger than the actual size of the object, such as 2:1, 3:1. In order to achieve high magnification, the lens needs to view at a relatively close distance, so it is called micro-distance.
Nearest Focus DistanceNearest Focus Distance
In close-range viewing, the image is magnified due to the shorter object distance. However, ordinary lenses can not be imaged at close range. This is because ordinary lenses are optimized according to the shooting distance multiplied by the focal length of the lens. When the object distance is 100 times the focal length of the lens, the lens performs best and all kinds of aberrations are well balanced. Beyond that distance, the balance is broken. However, due to the need of composition, optical manufacturers will still set the focus distance of the lens closer. For example, the most recent focus distance of 50 mm lens is about 45 cm. However, when viewing within 1 meter, there will still be distortion and serious edge light erosion (dark angle). When the focal plane is less than 45 cm away from the object, the lens will not be able to focus.
Note that the nearest focusing distance refers to the distance from the object to the focal plane, not to the front-end lens. The lens is marked with the nearest focusing distance, and the working distance of the front-end lens is smaller than this parameter. In order to achieve greater magnification, it is necessary to keep the lens closer to the subject. The nearer the focus distance is, the stronger the front-end lens can achieve. This method is the use of macro lens in macro photography. Micro lens is a kind of lens specially designed by optical manufacturers to achieve high magnification. In the design, the difference between close-range photography is corrected effectively and the price is expensive.
Effective apertureEffective aperture
The aperture F value of a lens refers to the ratio of the focal length to the aperture of the input light when the lens is focusing at infinity. When the focusing distance is not infinite, the ratio will increase. In general photography, the increase of F value of aperture is not obvious, but in macro photography, the effect of this increase will be significantly enhanced. In close range photography, the actual aperture F of the lens obtained is F = F * (1 + M). M refers to the magnification. When the magnification is 1:1, the effective aperture will be reduced by two gears. If the lens aperture is set to F4, the effective aperture value is F8 when 1:1 micro-distance is used. Modern cameras are equipped with TTL photometry system, so they can measure light accurately. However, when using a macro lens, we often feel that the light is too dim and that the slow door is easily blurred when shooting.
The image produced by optical system is different from that obtained by paraxial optics (Gauss optics). There is a certain deviation between optical imaging and paraxial imaging. Photographers can directly understand Gauss optical imaging as ideal imaging. Field aberration often occurs in macrophotography.