Please explain the character meaning of Pentax lens SMC Pentax-DA18-135mm F3.5-5.6 EDAL [IF] DC WR in detail.

SMC(Super Mluti Coating) Super Multilayer Coating: English full name, the lens marked with SMC indicates that Pentax's unique lens coating technology is used, which helps to improve the image quality and has strong anti-glare ability.

Da: that is to say, this lens belongs to a digital SLR camera and is marked with a green circle.

18-135mm focal length

F3.5-5.6 Maximum aperture 3.5

Aspheric lens

An ideal lens should gather light at one point, but unfortunately there is nothing absolutely perfect in this world. Because the light passing through the center of ordinary spherical lens and the surrounding light can not converge to one point, the so-called spherical aberration is caused, which affects the imaging quality. Using aspheric lens can alleviate this phenomenon and effectively control spherical aberration. This technique is often used for wide-angle lenses. Pentax aspherical lenses are generally made of thermosetting resin.

ED (ultra-low dispersion) glass: Because natural light is not composed of light of a single color, when it is refracted in glass, the imaging of various monochromatic lights will be different due to the different refractive indexes of various lights. Pentax uses ultra-low dispersion glass on some advanced FA* lenses to minimize the influence of dispersion, which can greatly improve the imaging quality of telephoto lenses.

IF (internal focus) internal focus technology is mainly used in high-end lenses. When focusing, only a part of the lens group inside the lens moves as a whole to achieve focusing. This kind of lens is characterized by constant length, high speed and no rotation of the front lens, which is beneficial to the installation of the filter. At the same time, it can also shorten the shortest shooting distance.

DC: lens motor

WR: waterproof lens

The simple summary is:

SMC coating

DA matches the lens of APS-C digital camera.

ED ultra-low dispersion lens

Aluminum aspherical lens

If the internal focus

direct-current motor

WR waterproof