What do the numbers on the SLR lens mean? How can I understand the numbers and text on the lens?

The meaning of the Canon lens logo: \x0d\\x0d\ Canon lens \x0d\\x0d\ Sort in alphabetical order \x0d\\x0d\ AFD: Arc-Form Drive arc motor\ x0d\\x0d\　 Curved DC motor developed for the AF drive of early EF lenses. Unlike the USM motor, the AFD motor focuses audibly. \x0d\\x0d\　DO: Multi-Layer Diffractive Optical Element Multi-layer diffractive optical element\x0d\\x0d\ On September 4, 2000, Canon announced the successful development of the world's first "multi-layer diffractive optical element" used in camera lenses. Layer Diffractive Optical Elements". Multi-layer diffractive optical lenses have the characteristics of both fluorite and aspherical lenses, so the launch of this lens is a milestone in the optical industry. The most important characteristic of diffractive optical elements is that the position of the wavelength composite image is opposite to that of the refractive optical element. In the same optical system, combining an MLDOE with a refractive optical element can correct dispersion (color diffusion) more effectively than a fluorite element. Moreover, by adjusting the pitch (gap) of the diffraction grating, diffractive optical elements can have the same optical properties as ground and polished aspherical lenses, effectively correcting spherical and other aberrations. \x0d\　Representative lens: EF 400/4 DO IS USM\x0d\\x0d\　EF: Electronic Focus Electronic Focus\x0d\\x0d\　The mount name of the Canon EOS camera is also the series name of the original EOS lens. \x0d\\x0d\　EMD: Electronic-Magnetic Diaphragm electromagnetic aperture\x0d\\x0d\ The accuracy is very high. \x0d\\x0d\　FL: Fluorite\x0d\\x0d\　A calcium fluoride crystal with extremely low dispersion and its ability to control chromatic aberration better than UD lenses. Strictly speaking, fluorite is not glass, but a crystal. It has a low refractive index (1.4) and is not affected by moisture. Fluorite lenses are generally not exposed to the outside, so you are unlikely to come into direct contact with them. Fluorite lenses are not as impact-resistant as ordinary glass, but they are not as fragile as imagined, so they do not require special care during use. \x0d\\x0d\　FTM: Full-time Manual Focusing\x0d\\x0d\　That is, no matter when, even when the lens is auto-focusing, you can manually adjust the focus without damaging the lens. \x0d\\x0d\　L: Luxury\x0d\\x0d\　The logo of Canon professional lenses. Compared with consumer-grade lenses, L-head lenses have ground aspherical lenses, UD (low dispersion), SUD (super-low dispersion) or Fluorite (fluorite) lenses, which are an important basis for the excellent optical quality of the lens. The build quality of the lens is generally much better as well. Its logo is the red reticle on the front of the lens, which is Canon's high-end professional lens. \x0d\　Representative lens: EF70-200/2.8 LU\x0d\\x0d\　IS: Image Stabilizer Image Stabilizer\x0d\\x0d\　The image stabilizer reduces the impact of hand shake on imaging by correcting the movement of optical components. Therefore, it is also called an anti-shake lens. The IS lens is equipped with a gyro sensor that detects hand vibration and converts it into an electrical signal. This signal is processed by a computer built into the lens and controls a set of correction optical components to move parallel to the film plane to offset the hand movement. Shift of imaging light caused by flutter. This system effectively improves handheld shooting, and for general purposes, IS lenses allow you to use shutter speeds two stops slower than theoretically possible. In other words, when you use an ordinary 300mm lens, you can only choose a speed above 1/250 seconds, but with a 300mm IS lens, you can take clear photos in 1/60 seconds. \x0d\?Representative lens: EF28-135/3.5-5.6 U IS\x0d\\x0d\?MM: Micro-Motor micro motor\x0d\\x0d\?This is a traditional motor with a transmission shaft. It consumes more electricity. Full Time Manual (FTM) is not supported. Mostly used for cheap low-end lenses. \x0d\\x0d\　SF: Soft Focus soft focus lens\x0d\\x0d\ The photos taken with this lens are very different from the effect of camera movement or incorrect focusing. It uses deliberately designed spherical aberration to This makes the scene being photographed clear in focus, soft and beautiful. The soft focus effect varies depending on the aperture size and the special adjustment device.

\x0d\ Representative lens: EF135/2.8SF\x0d\\x0d\ S-UD: Super Ultra-low Dispersion High-performance ultra-low dispersion lens \x0d\\x0d\ A piece of S-UD is roughly the same as using a piece of fluorite lens. similar. \x0d\\x0d\　TS: Tilt Shift lens\x0d\\x0d\　A lens that moves the optical axis of the lens to adjust the perspective. The function of a tilt-shift lens is not only to correct perspective distortion, but also to adjust the position of the focal plane. Under normal circumstances, the focal plane of the camera is parallel to the film plane. When shooting with a large aperture, the scene on the focal plane will be clear and the out-of-focus scene will be blurry. If you use a tilt-shift lens to adjust the focal plane, the sharp point can be changed. Obviously, tilt-shift lenses are best for architectural, landscape, and commercial photography. EF tilt-shift lenses do not have AF function. \x0d\ Canon’s TS lenses currently include TS-E24/3.5L, TS-E45/2.8 and TS-E90/2.8.\x0d\\x0d\ UD: Ultra-low Dispersion lens\x0d\\ x0d\　A special type of optical glass, which is widely used to control the chromatic aberration of lenses due to its ability to control the dispersion of light in the spectrum. Using two pieces of UD together has roughly the same effect as using one piece of fluorite lens. \x0d\\x0d\　USM/U: Ultrasonic Motor\x0d\\x0d\ The type of focus motor used by most EF lenses. A motor that uses a vibration source with a frequency in the ultrasonic range to rotate. It is the main method for achieving quiet and high-speed AF. part. There are two types of ultrasonic motors for EF lenses, ring ultrasonic motor (Ring-USM) and micro ultrasonic motor (Micro-USM). Lenses that use ultrasonic motors have a yellow ring on the front end, marked "ULTRASONIC". The ring ultrasonic motor is the focus motor used in Canon's mid-to-high-end USM lenses. Its driving component is ring-shaped and does not require the use of any transmission parts such as gears when driving. Because of the large torque, the starting and braking speeds are much faster than ordinary focus motors. Full-time manual operation can only be achieved in the ring-shaped ultrasonic motor head. Please note that EF 200/1.8L, EF 500/4.5L, EF 600/4L, EF 50/1.0L, EF 85/1.2L, etc. cannot achieve full-time manual operation. . The micro ultrasonic motor is a small cylindrical ultrasonic motor. It is not as fast and quiet as the ring ultrasonic motor, and it cannot be used for full-time manual focusing. However, due to its lower manufacturing cost, it is mostly used in mid-to-low-end EF lenses. \x0d\　Representative lens: EF24-85/3.5-4.5U\x0d\\x0d\ Nikon also has two categories: full-frame lenses and non-full-frame lenses. The difference in model between them is: non-full-frame lenses have " DX" logo\x0d\\x0d\ ① AF-S: The set of letters at the beginning of the model represents the focusing method of the lens. There have been "Ai" (manual focus), "Ai AF" (auto focus), and "Ai AF-S" ” (ultrasonic motor autofocus), “AF-S” (ultrasonic motor autofocus), “PC” (tilt-shift, manual focus), “PC-E” (tilt-shift, manual focus), etc., which are quite complicated. . But for now, just remember AF and AF-S. The former does not have an ultrasonic focus motor in the lens, while the latter does. It can achieve autofocus on SLRs without body focus motors such as D40, D60, and D5000. \x0d\　②NIKKOR: The collective name for Nikon lenses, so we may usually hear the term "Nikkor lenses". When we identify the lens, this NIKKOR has little meaning and can be ignored. \x0d\　③70-200mm (18-200mm): This is the focal length of the lens. A range (such as 70-200mm) means that this is a zoom lens. There is no range and only a fixed value (such as 50mm), which means this is a zoom lens. Prime lenses only. \x0d\　④f/2.8 (f/3.5-5.6): This represents the maximum aperture value of this lens at different focal lengths. If the maximum aperture value of the zoom lens is a fixed value (such as f/2.8), it means that this is a constant aperture lens, which can maintain a certain maximum aperture at the wide-angle end and telephoto end of the lens; if the maximum aperture value of the zoom lens It is a range value (for example, f/3.5-5.6). The first value represents the maximum aperture of the lens at the wide-angle end, and the latter value represents the maximum aperture of the lens at the telephoto end. If it is a fixed focus lens, the maximum aperture is a fixed value (except for special lenses). \x0d\　⑤G: Today’s Nikon lenses mainly include D type and G type. The earlier D type, which stands for Distance, is a unique function of Nikon. It can transmit the lens focus distance information to the body to achieve more precise exposure control, 3D-RGB matrix metering, i-TTL flash and other features. . The G-type lens is a new type of lens that eliminates the aperture adjustment ring. While maintaining the distance information transmitted by the D-type lens, it optimizes the shooting operation with automatic SLRs.

However, since the aperture cannot be adjusted on the lens, G-type lenses can only be shot at the maximum aperture on some Nikon fully manual SLRs, or when mounted on other brands of SLRs through an adapter ring. \x0d\　⑥ED (Extra-low Dispersion) lens: The abbreviation of Extra-low Dispersion. Generally, lenses made of optical glass have a certain degree of dispersion. The longer the focal length, the more obvious the dispersion becomes. The ultra-low dispersion glass developed by Nikon can effectively reduce dispersion. In addition to ED lenses, Nikon also has Super ED lenses, which provide better dispersion elimination effects. (ED lenses correspond to Canon's UD lenses) \x0d\ ⑦ VR (optical anti-shake): The abbreviation of Vibration Reduction, similar to Canon's IS, both detect the shake of the lens through the sensor in the lens, and then drive the optical components in the opposite direction. Compensate for image blur caused by jitter. The latest second-generation VR can achieve the effect of lowering the safety shutter up to four levels. \x0d\　⑧II: Represents the second generation of lenses with the same specifications (optimized and improved version, etc.). \x0d\　⑨DX: The name of Nikon's non-full-frame digital SLR format, and the corresponding Nikon full-frame digital SLR format is FX. Nikon lenses with the DX logo are small image field lenses that are not dedicated to full frame. But unlike Canon, Nikon's DX lenses can also be installed and used on FX full-frame digital SLRs, but they will appear around the shot. A black circle (FX full-frame SLR has DX mode, which automatically crops the part in the middle of the picture that is not affected by the imaging circle). \x0d\\x0d\　Examples of Nikon lens feature markings\x0d\ In addition to the above model markings, Nikon lenses also have many feature markings. As shown in the example above, the gray ones are the features that this lens does not have. Now let’s Analyze it (the parts that have been explained before will not be explained below). \x0d\　1. AS: The abbreviation of Aspherical Lens, that is, aspherical lens. Because traditional spherical lenses inevitably have certain visual defects in optics (spherical aberration - the higher the power of the positive and negative mirrors, the more obvious the prism effect. That is: the light is refracted toward the base and the object is displaced toward the top). For this reason, modern lenses continue to innovate in design and create new "aspherical" designs. The curved surface of an aspherical lens no longer has the same curvature, that is, it is no longer a spherical surface. Lenses can be made thinner, reducing marginal aberrations. \x0d\　2. SC: The abbreviation of Nikon Super Integrated Coating, that is, Nikon Super Integrated Coating. Developed on the basis of traditional multi-layer coating, it can achieve high light transmittance in a wide wavelength range and reduce glare and ghosting. \x0d\　3. IF: The abbreviation of Internal Focusing, that is, internal focusing. Focusing is achieved by moving the middle group of lenses in the lens. Since there are fewer and lighter lenses that need to be moved, the requirements on the focus motor can be reduced and faster focusing can be achieved. \x0d\　4. RF: The abbreviation of Rear Focusing, that is, rear group focusing. Characteristics are similar to IF and are often used in short focal length lenses. \x0d\　5. CC: The abbreviation of Close-Range Correction System, also referred to as CRC, is the close-range (focus) correction system, which is also commonly known as the independent floating optical lens group. Its function is to improve the focus when focusing at close range. Stability and picture sharpness. \x0d\　6. SWM: The abbreviation of Silent Wave Motor, which is Nikon’s version of “ultrasonic focus motor”. Like Canon USM, it uses sound waves to drive focus. Nikon's lenses with SWM are marked with "AF-S" at the beginning of the lens model number, so you should read it carefully. \x0d\　7. M/A: The abbreviation of MF/AF, which is Nikon’s version of “full-time manual focus”. Seamless switching between manual focus and autofocus can be achieved without switching focus mode. In M/A mode, MF manual focus takes priority. \x0d\　8. A/M: The abbreviation of AF/MF is similar to M/A above, except that in this mode, AF autofocus is given priority. \x0d\　9. A-M: The abbreviation of AF-MF. Different from A/M, A-M means that AF and MF are switched by a switch. \x0d\　10. RD: The abbreviation of Rounded Diaphragm, that is, circular aperture. The shape of the aperture blades is close to a perfect circle, which can make the out-of-focus image of the lens smoother and the blur more beautiful. \x0d\　11. N: The abbreviation of Nano Crystal Coat, which is nanocrystalline coating. Nano Crystal Coat is an anti-reflective coating that was first used in the NSR series (Nikon Step-Repeat System) semiconductor manufacturing equipment. Nano Crystal Coat virtually eliminates internal lens reflections at various wavelengths and very effectively reduces image ghosting and flare that are characteristic of ultra-wide-angle lenses. Nano Crystal Coat uses a multi-layer Nikon ultra-low refractive index coating, which has nano-scale ultra-fine crystalline particles. \x0d\　12. DC: short for Defocus-image Control, that is, out-of-focus image control.

Through a set of special lenses, the blur effect of the front and rear depth of field is controlled at the same aperture. \x0d\　13. ML: The abbreviation of Meniscus Protective Lens, that is, spherical protective lens. The first lens in front of a large telephoto lens is actually used to protect the lens. It is usually a flat glass lens. However, when exposed to strong backlight, it will produce obvious reflections inside the lens, causing ghosting. The spherical protective lens is manufactured with a specific curvature, which can effectively reduce the internal reflection of the lens in the above situations.