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form the shape of the aperture blades close to a circle, let the lens focus image more smooth, blur even more beautiful.
As the traditional spherical lens
Canon EF lenses on the basis of size by reducing the image circle to meet the APS-C (non-full frame) digital SLR the smaller sensor. EF-S series lenses have a lower design, manufacturing costs, for entry-level digital SLR to use (of course there are the advanced EF-S lenses), but the EF-S lenses can not be used on the Canon full-frame SLR, lenses and machine damage the body.

general design of the lens, focus distance in common with the best aberration correction, but may in the recent shooting aberration from the end when the case. Floating focusing system can be extended with the length of the lens, moving a whole group of lens that allows close-described improve quality. Mainly high-end macro lens has taken the technology to varying degrees, moving within the same optical system lens group, taken at different focal lengths and different from the case of shooting, and hunting can achieve a clear image to reduce the dispersion effect. Floating focus system, in close-ups to achieve the best quality, the macro lens and ultra-wide-angle lens on the effect is particularly prominent.
⑤ IS:
③ f/2.8 (f/3.5-5.6):
4, full-time manual focus:

10, fluorite (Fluorite) Lens:
5, IS (IMAGE STABILIZER, image stabilizer):
optically inevitable in the presence of a certain visual defects (spherical aberration, the higher the degree of positive and negative lens, prism effect is more obvious that : refraction of light to the basement, objects to the top displacement). Modern lenses for this continuous innovation in the design, creating a new type of Aspheric lens surface curvature is not one and the same, that is not a sphere. Can make lenses thinner, reducing the edge of the aberrations.
3, IF / RF (Internal Focus / Focus after):
by ultrasonic vibrations into rotational energy of this new principle, to achieve almost silent operation of the sound of the lens drive motor. In 1987, the first time be applied to the Canon EF 300mm f/2.8L USM, shocked the world of the photographer. And, also with low power consumption to achieve a high efficiency, high torque, high sensitivity,timberland site, high-speed focusing. Now, almost all EF lenses are equipped with USM. Cylindrical arc, easy to load round the lens barrel ring USM, only simple in structure, but also has a very excellent driving performance. -30 ℃ to +60 ℃ in the temperature range, can work,hollister outlet, calmly severe shooting conditions. Subsequent development is not subject to restrictions on micro-lens aperture USM. Due to lower cost, can be applied in more lens, further expanding the versatility. And, with the miniaturization of the lens itself, but also the development of length and weight are about half of the ultra-micro USM micro-USM II, is expected to generally be used in future micro-zoom lens.
Canon developed the UD (Ultra Low Dispersion = low dispersion) lens is a low-refraction, low dispersion characteristics of optical lenses. Two UD lenses get almost the same with a high-performance fluorite lens optical properties. Canon lenses in the development of the UD, after persistent efforts in 1993 to develop a substantial increase in UD lens optical performance of the For the lens further miniaturization of high performance and contribute widely used standard, telephoto, super telephoto and other lenses.
11, DO (diffractive optics) lens:
① EF:

Canon models to explain
that using IS (IMAGE STABILIZER) image stabilization, that is, optical image stabilization feature.

identify features Canon lens case
⑧ EF-S:
on behalf of the second generation of the same size lens (optimized and improved version of the class).
12, SWC (sub-wavelength structure coating):
generally divided into two series Canon lens (Canon EF series lens is full frame, non-full-frame EF-S lens series), the figure is one of the representatives, we can see what the difference in two models, Please note the following detailed explanation of model number.
7, floating focus:
lens diameter divided by the number of local, mobile or middle part of the last part of the focusing lens group approach. In addition, after the application is still in focus zoom lens. For the zoom lens, useful outside the front lens group for focusing lens group, as well as the former group is divided into two parts, with the second half of the lens group to focus in two ways. And, because the filter mounting frame does not rotate, so polarizing filters with excellent handling.
Source: pconline 2010 年 02 月 24 日 Author: Dumplings Editor: liangjiaxian
1, USM (ultrasonic motor):
shooting a major obstacle is the Usually in order to avoid jitter, we need a faster than However, if in a dark place or the use of low sensitivity when shooting handheld, you must slow down the shutter speed, so it is easy to make the footage blurred. When the lens shift due to jitter, the beam from the subject and the lens optical axis will be bias, resulting in blurred images. The vertical plane through the optical axis direction to move the optical system, according to the degree of adjustment of the lens jitter amount of movement to keep the beam steady state, to complete the image compensation. Testing jitter is mounted in the lens of two anti-impact vibration gyro box. And through the small, lightweight, and has excellent responsiveness and control of the moving coil, direct drive compensation optical system. Moreover, the position of the optical system of compensation by IRED (infrared emitting diode) and PSD (position sensing components) testing, the feedback control. In addition, IS image stabilization unit is also equipped with compensation after the end of the shake compensation optical system fixed to the central locking mechanism.
that lens auto focus is the use of ultrasonic motor as power source.
is the abbreviation of the English luxury

④ L:
8,tods handbags, dust and water drops:
9, aspherical lens:
FAQ lens Nikon lens model identifies the mystery Detailed Canon (Canon papers)
is calcium fluoride (CaF2) crystal formation. It was characterized by very low refractive index and dispersion of infrared, ultraviolet transmittance good. But another point of concern: it has a general optical glass can not be achieved bright, delicate description of the performance. Because the light generated by the general focus of the lens color deviation will be divergent, so that the sharpness of the image taken down, which we call color. Dispersion fluorite lens because the light little, almost no color, so the lens is ideal for photographic use. Canon has developed in the late 1960s the artificial crystal fluorite generation technology, and the white lens, super telephoto L series lens uses fluorite lens. SLR camera lens in use on only Canon fluorite,hollister swim, its description of the delicate and high-contrast, has been highly appreciated by photographers around the world.
to keep switching from autofocus to manual focus, with a ring USM (ultrasonic motor) is equipped with all EF lenses and micro USM, EF 50mm f/1.4 USM lenses have the feature.
⑦ USM:
SWC is SubWavelength Structure Coating of shorthand, which is a use different from the ordinary principles of vapor coating to prevent light reflection of the new coating technology. The phenomenon of light reflection surface of the lens, the lens is due to the boundary of glass and air refractive index caused by sudden changes. Reflection can produce glare and ghosting affect image quality. To suppress light reflection, the refractive index between air and glass should be gradually reduced. Between air and glass if there is a way to smoothly change the refractive index of the coating, the light entering the lens from air to glass or from glass to air, it will not produce a lot of reflection. This is the sub-wavelength structure coating (SWC) anti-reflection principle. SWC in the surface of the lens is less than the wavelength of visible light to form a wedge-shaped micro-structure, this structure can continue to change the refractive index, thereby eliminating the sudden change in the refractive index of the border, to achieve better than the vapor coating inhibitory reflex effect.
parts used in the lens mount and camera body to increase to plug the gap between the rubber gasket of the water drops dust structures; and the focus ring, focus preset Play ring movable parts of the water droplets also take appropriate dust control measures. In addition, the camera control panel and the back of the cartridge filter slot interface also uses a rubber material, to improve the details of some of the camera waterproof and dustproof performance drops.
This is representative of this lens at different focal lengths of the maximum aperture. If the maximum aperture zoom lens is a fixed value (eg f/2.8) on behalf of this is a constant aperture lens, the lens wide-angle end and telephoto end can maintain a maximum aperture; if maximum aperture zoom lens value is a range of values ​​(for example, f/3.5-5.6), a value representing the front of the lens's maximum aperture at wide angle end, followed by a numeric value represents the maximum lens aperture at the telephoto end. If it is fixed focus lens, maximum aperture is a fixed value (except for special lenses).
This is the lens focal length, a range (eg 70-200mm) on behalf of this is a zoom lens, there is no scope, only one value (eg 50mm) on behalf of This is a fixed focus lens.
In addition to the logo on the lens model, the lens has different features or functions identified, will also appear in other parts of the lens models, let's take a look.
6, circular aperture:
⑥ II:

② 70-200mm (15-85mm):
diffractive optical elements with refractive optical element has exactly the opposite on the color of nature. DO take advantage of these properties through the lens, chromatic aberration theoretically achieve a Canon developed its own DO lens with double layer glass lens surface is made of precision to micron precision diffraction grating close to each other to form a layered structure. With continuous research diffractive optical elements of the material, shape and structure, etc., Canon successfully developed by the three-layer diffractive optical elements to form the three-layered structure of DO lenses. Incoming light will no longer be unnecessary in light refraction, light is almost completely used for shooting, this telephoto zoom lens to achieve miniaturization.
2, UD (ultra-low dispersion lenses):
lens series name, the Canon EF lens mount is a bayonet, the Chinese name is no mechanical transmission structure, all in electronic contact operation. (Full-frame Canon EF series lens, the lens is non-full-frame EF-S series)
. If the name in the Canon lens with the L is a clear sign of the lens barrel on the eye-catching red circle.
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