They are called "pancakes", and their main task is to be compact. Great lens for everyday use. Finally, now the "SLR" can be carried in a bag without taking up much space in it. The viewing angle is larger than that of the main competitor - Canon EF 50 f1.8, while, in comparison, it is almost silent and the design is more reliable. The size of the frame for the light filter is 52 mm, like the "whale" 18-55. I tried to catch the "hares" in the backlight - it did not work out. Of course, it doesn’t pull on a clean “portrait” because of the aperture ratio, but as a “fix” for everyday use it is very convenient. I didn’t shoot a video with him (I have the 450th), but by the abbreviation STM it’s clear that it was created for video shooting.
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