What do the letters USM on your Canon SLR camera lens mean?

If you notice your Canon digital SLR camera lens has the letters USM written on the side, it means the lens has a small motor built into the body. Hence, USM is short for Ultra Sonic Motor. What this means is that your lens will autofocus faster than standard models.

Canon USM lenses

It is important to note that there are two different types of USM lenses. A Ring ultrasonic, is the one you want to purchase. Then there are Micromotor ultrasonic drives that Canon places into their cheaper lenses. Unfortunately, they also letter these cheaper versions with USM as well. While these cheaper versions are quieter, they don’t however focus as quickly as a true ring ultrasonic lens. Therefore, you need to check the lens specifications before purchasing to ensure it is a ring ultrasonic lens, and not a cheaper version created for what is rumored to be marketing reasons.

What are the advantages of using Canons range of ring USM camera lens?

  • The main advantage of using a ring USM, is that the motor is built into the lens so that it can auto focus faster than a standard lens.
  • Canon’s USM / UltraSonic Motors, are also famous for being quieter than standard motors used in cheaper lenses. This is useful for wildlife photographers, where animals and insects could become spooked from noisy camera parts.

Are there any disadvantages to using a USM camera lens?

  • A USM lens will cost you a little extra than one without it.
  • USM lenses are generally heavier than standard ones. You might need to take this into account if like me, you tend to carry around 3 at a time.

Current list of Canon Ring Ultrasonic / USM camera lenses include:

EF 16-35mm f/2.8 L II USM
EF-S 10-22mm f/3.5-4.5 USM
EF 17-40mm f/4 L USM
EF 20-35mm f/3.5-4.5 USM
EF-S 17-55 f/2.8 IS USM
EF-S 17-85MM f4-5.6 IS USM
EF 24-70mm f/2.8 L USM
EF 24-85mm f/3.5-4.5 USM
EF 28-105mm f/3.5-4.5 II USM
EF 24-105mm f/4 L IS USM
EF 28-135mm f/3.5-5.6 IS USM
EF 28-300mm f/3.5-5.6 L IS USM
EF 70-200mm f/2.8 L IS USM
EF 70-200mm f/2.8 L USM
EF70-200mm f/4 L IS USM
EF 70-200mm f/4 L USM
EF 70-300mm f/4.5-5.6 DO IS USM
EF 100-300mm f/4.5-5.6 USM
EF 100-400mm f/4.5-5.6 L IS USM
EF 14mm f/2.8 L II USM
EF 14mm f/2.8 L USM
EF 20mm f/2.8 USM
EF 24mm f/1.4 L USM
EF 35mm f/1.4 L USM
EF 28mm f/1.8 USM
EF 50mm f / 1.2 L USM
EF 85mm f/1.2 L II USM
EF 85mm f/1.8 USM
EF 100mm f/2 USM
EF 135mm f/2 L USM
EF 200mm f/2.8 L II USM
EF 300mm f/4 L IS USM
EF 300mm f/2.8 L IS USM
EF 400mm f/2.8 L IS USM
EF 400mm f/4 DO IS USM
EF 400mm f/5.6 L USM
EF 500mm f/4 L IS USM
EF 600mm f/4 L IS USM
EF-S 60mm f/2.8 Macro USM
EF 100mm f/2.8 Macro USM
EF 180mm f/3.5 L Macro USM