Anti-reflection coating (anti-reflection coating) is a multilayer coating

　　 The light transmittance of resin or glass lens cannot reach 100%, and some light will be The two surfaces of the lens reflect back, and the higher the refractive index, the higher the reflectivity of the lens. Resin 4%, glass 4.3%.

The reflection of the 　　 lens can reduce the light transmittance and form an interference image on the retina, which affects the quality of the image and the appearance of the wearer. For example, the appearance of the lens is obviously vortex, and the eyes of the wearer cannot be seen by the opposite light.

　　 The anti-reflection coating is the most commonly used optical coating. It is based on the wave of light and the principle of interference, so that the reflected light of the mirror and the reflected light of the coating interfere with each other. eliminate. Different film layers selectively eliminate the reflection of light in the corresponding wavelength band, remove the interference of the dry optical lens, and increase the visible light transmittance to improve the image quality. Make the image clearer and reduce visual fatigue. It can also selectively reduce the penetration of harmful rays in certain wavelength bands, such as ultraviolet rays, X-rays, etc., to reduce the damage of these rays to the eyes and protect the eyes from their harm.

　　 There are currently nine layers of anti-reflection coatings for resin lenses, and the reflectivity has been reduced to about 0.2% , So that the light transmittance of the resin lens can reach 99% or more. Greatly improve the quality of imaging and obtain the best correction effect.

　　Top film (waterproof film, anti-fog film)

　　 Due to the technical needs of anti-reflection film, the film is intermolecular The gap is large, and the surface of the lens is easy to hold dirt.

　　The top film material has small molecular particles and small gaps between the molecules, which makes the surface of the lens more smooth and clean, and adds the functions of waterproof, anti-fog, dust-proof and other anti-pollution functions to the optical lens. .

　　Abrasion resistant film (commonly known as hard film)

　　The base of the resin lens is softer, on a hard object Sliding over, the anti-reflection coating on the lens is prone to scratches, which will affect the transmittance of the lens and the effect of the film. Therefore, in order to improve the wear resistance of the lens, the researchers used the soaking process to plate a material with high hardness and not brittle cracking on the surface of the organic lens, that is, a hard-wear film.

　　 is more suitable for outdoor and changeable environments

　　The optical lens has a small aperture in the long focal length, so when shooting in a low light environment It will be more difficult. As for the image quality, since the light passes through a lot of lenses and undergoes multiple refraction, the image sharpness and dispersion performance are basically slightly inferior to focusing lenses than fixed focus and lower zoom lenses. Similarly, narrowing the aperture will also help the picture quality. However, in order to take into account the quality problem, the optical lens group will have more high-quality lenses. For example, Nikon’s two optical lenses have two ED ultra-low dispersion lenses and 4 SLD (Special Low Dispension) lenses. Quality performance can still maintain a certain level.

　　 Is the optical lens worth having? It depends on the user's habits. The author is not opposed to buying optical lenses, especially for those who are really leisure-oriented and do not plan to buy more lenses. The wide focal length can be very convenient for use. For example, you can take pictures when you go sightseeing and parade in floats. Large scenes, at the same time, you can choose a close-up of the target shadow without changing the lens. Although the optical aspheric lens does not have the advantage of a large aperture, most of the lenses are equipped with optical anti-shake, which can be used in the hand with a slower shutter to maintain clarity. Most of the SLRs on the market have excellent noise processing capabilities, and the image quality of higher ISO also has a certain level.

　　 The author also tried this experience in beach volleyball matches, a wide-angle zoom and a long-distance It is very troublesome to replace the zoom lens with large aperture frequently in the field. In fact, there are two solutions. Professional photographers will prepare two cameras and two lenses for real-time exchange. For users who only have one camera, hold an 18-200mm (APS-C camera as an example) optical lens. It is a good choice, especially in a sunny environment, although the aperture is relatively small, it can still be coped with a higher ISO and high-speed shutter.