What Is USM On Canon Lens?

what is USM on Canon lens featured photo

Do you ever wonder about the meaning of the random letters on a Canon lens? You are not alone. When I got my very first Canon lens years ago, I also felt confused about designations like USM and STM. So I did my own research and discovered the USM lens meaning.

USM stands for Ultra Sonic Motor. It is a type of autofocus motor that delivers smooth and quiet autofocusing performance. It can help you focus on a moving subject faster than a normal Canon lens without the USM designation.

This article will cover more features of the USM lens from Canon. I will also show you the pros and cons of using it. Plus, I will teach you the different types of USM lenses.  

What Is USM On Canon Lens?

USM lens from Canon

USM is an abbreviation for Ultra Sonic Motor. It is an autofocus motor produced by Canon for its EOS lenses.

USM lenses are known for their precise, quick, and silent autofocus. They can help you capture both stationary and fast-moving subjects in sharp detail.

USM technology was first introduced in 1987. It was launched alongside the Canon EF 300mm f/2.8L USM lens. From there on, Canon continued to develop lenses with Ultra Sonic Motor. The manufacturer also produced variations of the AF technology, which I will cover later on.

What Are The Advantages of Canon USM Lenses?

Canon lenses with the USM designation offer several benefits.

First and foremost, USM lenses provide fast autofocus speeds. The built-in AF motor can quickly rotate lens elements to focus on fast-moving subjects, such as birds, wildlife, and children.

The USM motor also ensures accurate focusing. It works alongside the camera to identify the correct focus points. The result is sharper and more detailed images.

Plus, the Canon USM system is relatively quiet compared to other autofocus motors from different brands. It is suitable for situations where noise is prohibited or disruptive, such as shooting in a church or recording video.

Finally, most USM lenses allow full-time manual focus override. This feature lets you adjust the focus manually without switching to autofocus mode. It comes in handy for instances where you need to focus on different subjects quickly.

For example, when taking a video of a birthday celebration, I was mostly focused on the celebrant. However, I also noticed the genuine emotions of the attendees, so I wanted to capture that as well. Thanks to my USM lens, I could quickly change to manual focusing mode despite shooting in autofocus mode. That would be impossible with a non-USM lens.

What Are The Disadvantages of Canon USM Lenses?

While USM lenses have several advantages, they also have a few downsides.

First, Canon lenses with USM technology tend to be more expensive than other types of autofocus motors. That is because the manufacturer spends more money and effort on designing the USM system.

The Ultra Sonic Motor can also add to the size and weight of the Canon lens. It can make the gear less portable, which might be a turn-off to photographers who often travel. A heavier lens is also more tiring to use for long periods.

Also, remember that no mechanical system is perfect; there is always potential for failure. While it rarely happens, fixing a failing USM lens can be expensive.

And although USM lenses have silent autofocus, they are not noiseless systems. They might not be the best choice for recording video. Consider newer autofocus technologies because they provide even quieter and smoother performance.

What Are The Different Types Of USM Lenses?

As previously mentioned, Canon developed variations of the original USM system to cater to different lens designs and photography requirements. As of 2023, there are four main types of Canon USM technology.

Ring-type USM

This is the first type of USM motor sold at the consumer price level. Developed in 1990, the ring-type USM uses a rotor and a stator, which is an elastic body with a piezoelectric ceramic voltage element. The rotor is connected to the focusing group, whereas the stator is attached to the lens barrel.

When the stator receives an alternate current (AC) with a frequency of 30kHz, it vibrates at ultrasonic frequencies (hence the name of the AF system). The generated ultrasonic waves cause the rotor to move in a rotational manner. As such, it can adjust the lens focus depending on the direction, speed, and degree of rotation.

A ring-type USM motor allows full-time manual focusing (FTM). It lets you switch from auto to manual focusing with ease. 

Micro USM

Micro USM lenses were introduced for consumer lenses in 1992. They combine the rotor, stator, and drive gear into a single mechanism half the weight of a ring-type USM motor. This AF technology can fit in different lenses without being restricted to the barrel size. 

Despite their unique design, micro USM lenses work similarly to ring-type USM lenses. The piezoelectric elements inside the stator create ultrasonic vibrations. These movements drive the gears of the focusing mechanism. 

However, micro USM lacks full-time manual focusing. It also tends to be noisier.  

Micro USM II

The Micro USM II motor was launched in 2000 with the Canon EF 28-105mm f/4-5.6 USM lens. It is basically a smaller version of the Micro USM motor and is designed to fit ultra-compact zoom lenses.

The reduced size was made possible by reconfiguring the rotor and stator. Canon placed part of the stator inside the rotor instead of aligning them together. They produced a new type of vibration with a lower resonant frequency, which delivers insufficient vibrational amplitude.

Nano USM

The Nano USM is the latest AF mechanism from Canon. It combines features from the ring USM and the STM lens. The goal is to provide fast autofocus for pictures and smooth adjustment for videos.

Similar to its predecessors, the Nano USM motor uses ultrasonic vibration to drive the focusing group. However, the movement is more linear than rotational. It results in smooth, fast, and near-silent performance. 

What Is STM? How Is It Different From USM Canon Lens?

How Is It Different From USM Canon Lens

When learning about USM lenses, you might have encountered the term “STM.” That does not come as a surprise since it is closely related to the USM system.

STM stands for Stepping or Stepper Motor, which is another type of autofocusing technology that Canon uses. It features a geared motor that drives the focus ring. The power comes from the camera instead of the lens itself.

Stepper Motor technology works by using direct current that passes through organized multiple coils. These connect to the AF group. When a pulse of current is received, the motor rotates in fixed steps. It results in smoother and more precise autofocusing performance. 

Canon STM lenses are suitable for capturing videos because of their smooth and quiet movement. However, unlike USM lenses, they tend to be slow because they rotate the motor one step at a time. They also do not offer full-time manual focus override, which limits the type of videos you can shoot.

Which Canon Lens Is Better: STM vs. USM?

Now that you understand STM and USM technologies, you might be curious to know which Canon autofocus system is better.

However, the best option depends on your unique needs and the type of content you are shooting. Canon did not produce USM and STM with the same purpose in mind, so they suit different needs.

Canon STM lenses have a smoother and quieter autofocus system than their USM counterparts. That is because they move the AF elements in fixed, consistent steps. These make STM lenses more suitable for videography.

On the other hand, Canon USM lenses offer faster performance due to ultrasonic vibrations driving the AF motor. While relatively silent, they can be noisier than STM models. The system might be better for photographers.

Before making a choice, you must also consider the manual focus override option. STM lenses do not offer this feature, while USM lenses have it. It is useful if you want to focus quickly on a subject while still in autofocus mode. 

As for the image quality, both autofocus systems are neck and neck. There is little difference between them, so I recommend getting the cheaper lens. However, as mentioned, USM technology can offer faster performance. It might be a better choice if your work involves events, sports, or wildlife. But if you do not want to disturb or scare off the subject (e.g., insects) because of noisy autofocus, get the STM lens.

At the end of the day, choosing between STM and USM lenses boils down to preference and intended application. 

List Of Current Canon USM Lenses

Below is a list of Canon lenses with Ultra Sonic Motor (USM).

EF Lenses

These lenses fit DSLR cameras with a full-frame and APS-C sensor. When attached to an APS-C camera, the lens will have a 1.6x crop factor. For example, a 35mm lens will have an equivalent focal length of 55mm.

  • Canon EF 14mm f/2.8L II USM
  • Canon EF 20mm f/2.8 USM
  • Canon EF 24mm f/1.4L II USM
  • Canon EF 28mm f/1.8 USM
  • Canon EF 35mm f/1.4L II USM
  • Canon EF 50mm f/1.2L USM
  • Canon EF 85mm f/1.2L II USM
  • Canon EF 85mm f/1.4L IS USM
  • Canon EF85mm f/1.8 USM
  • Canon EF 100mm f/2 USM
  • Canon EF 100mm f/2.8 Macro USM
  • Canon EF 135mm f/2L USM
  • Canon EF 180mm f/3.5L Macro USM
  • Canon EF 200mm f/2L IS USM
  • Canon EF 300mm f/2.8L IS II USM
  • Canon EF 400mm f/2.8L IS III USM
  • Canon EF 500mm f/4L IS II USM
  • Canon EF 600mm f/4L IS III USM
  • Canon EF 800mm f/5.6L IS USM
  • Canon EF 8-15mm f/4L Fisheye USM
  • Canon EF 16-35mm f/2.8L III USM
  • Canon EF17-40mm f/4L USM
  • Canon EF 24-70mm f/2.8L II USM
  • Canon EF 24-105mm f/4L IS II USM
  • Canon EF 28-300mm f/3.5-5.6L IS USM
  • Canon EF 70-200mm f/2.8L IS III USM
  • Canon EF 70-200mm f/4L IS II USM
  • Canon EF 70-300mm f/4-5.6 IS II USM
  • Canon EF 75-300mm f/4-5.6 III USM
  • Canon EF 100-400mm f/4.5-5.6L IS II USM

EF-S Lenses

EF-S lenses have a smaller image circle than EF lenses, resulting in a 1.6x crop factor. They are only compatible with APS-C or crop-sensor cameras.

  • Canon EF-S 60mm f/2.8 Macro USM
  • Canon EF-S 10-22mm f/3.5-4.5 USM
  • Canon EF-S 15-85mm f/3.5-5.6 IS USM
  • Canon EF-S 17-55mm f/2.8 IS USM
  • Canon EF-S 17-85mm f/4-5.6 IS USM
  • Canon EF-S 18-135mm f/3.5-5.6 IS USM

RF Lenses

These types of lenses are designed for full-frame mirrorless cameras.

  • Canon RF 50mm f/1.2 L USM
  • Canon RF 85mm f/1.2 L USM
  • Canon RF 100mm f/2.8L Macro IS USM
  • Canon RF 135mm f/1.8L IS USM
  • Canon RF 400mm f/2.8L IS USM
  • Canon RF 600mm f/4L IS USM
  • Canon RF 800mm f/5.6L IS USM
  • Canon RF 1200mm f/8L IS USM
  • Canon RF 14-35mm f/4L IS USM
  • Canon RF 15-35mm f/2.8 L IS USM
  • Canon RF 24-70mm f/2.8 L IS USM
  • Canon RF 24-105mm f/4L IS USM
  • Canon RF 24-240mm f/4-6.3 IS USM
  • Canon RF 28-70mm f/2 L USM
  • Canon RF 70-200mm f/2.8 L IS USM
  • Canon RF 100-300mm f/2.8L IS USM
  • Canon RF 100-400mm f/5.6-8 IS USM
  • Canon RF 100-500mm f/4.5-7.1 L IS USM


When shopping for Canon lenses, you might encounter different letters, such as USM. It is important to understand their definitions before buying a lens.

USM stands for Ultra Sonic Motor. It is an autofocus system known for its fast, accurate, and silent autofocus. It also has a manual focus override, which is ideal for different instances.

Do you have other questions about Canon USM lenses? Drop by our contact page to send your queries!