EX, advanced lens, similar to Canon's "L" and red circle mark.

OS, image stabilizer, similar to Canon's IS.

HSM, ultrasonic motor, similar to Canon USM.

Macro, macro, not micro, the magnification is relatively high. Generally speaking, the macro can be more than 1:5, and the macro lenses of big factories can generally be 1: 1 or 1:3, but Sima can't.

APO, achromatic optical design, has nothing to do with low dispersion or ultra-low dispersion or fluorite lenses. It is through the design of optical structure that chromatic aberration is eliminated, which has appeared since 18- 19 century, while low dispersion lenses only existed in the 20th century. The place that tests the optical design ability most, the pain point of all optical manufacturers in Asia, Sigma has always been relatively strong, but it is not as good as any German APO.

DG, the digital camera is optimized. Compared with the previous lens rear group, it has better coating treatment to prevent light from reflecting between the low-pass filter and the lens rear group of the digital camera.

DC, with a small frame, can be normally used in the fuselage of APS-C frame. On the Quan Huafu fuselage of 135, you will see obvious dark corners and even shadows.