On Canon lenses, you’ll notice STM and USM depending on the type of lens. STM stands for Stepper Motor, and USM stands for Ultrasonic Motor.
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Canon STM lens
When you use a lens from Canon that’s labeled with STM, that means it has Canon’s Stepper Motor technology. It’s a design for the focus motor that makes the autofocus quiet and smooth.
The photos that you take with an STM lens will turn out well. However, they really shine with videos.
The Stepping Motor technology allows you to record videos without hearing the lens autofocusing. The attention and focus will be on what’s in the video instead of the lens.
Canon USM lens
Canon lenses that are labeled with USM means that it features an Ultrasonic Motor. The USM lenses offer faster autofocus, are built with better quality, and are geared towards professionals.
It works by converting ultrasonic vibration energy into rotational force to move the lens. It’s the fastest focusing motor that Canon currently offers.
The only drawback is that USM lenses aren’t as quiet as STM lenses. However, they’re still pretty quiet when it comes to autofocus.
Direct Drive Motors
Some lenses won’t have STM or USM on them. If that’s the case, it means that the lens uses the traditional direct drive motor (DC). It’s not as technologically advanced, which means it won’t be as fast, quiet, or smooth.
STM and USM lenses are better than DC lenses. If you’re a videographer or amateur photographer, STM lenses are the best. If you do photography for a living, take still-life photos and portraits, USM lenses are better. Overall, USM lenses cost more due to the advanced technology.
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