USM
USM is simple enough like IS it is an anagram for Ultrasonic Motor
When you focus a camera there are a lot of moving parts. Ultrasonic Motor means that the motor moving your Len's elements is going to be silent or at least close to it.
In other manufacturers other then canon it goes by other names
When you focus a camera there are a lot of moving parts. Ultrasonic Motor means that the motor moving your Len's elements is going to be silent or at least close to it.
In other manufacturers other then canon it goes by other names
- Tamron- USD which means Ultrasonic Drive
- Sigma- HSM which means Hyper-Sonic Motor
WHY SHOULD YOU CARE
It all depends on what kind of photographer you are going to be.
As a sports photographer in football no one cares if you lens makes a little bit of a hum. But in golf they might care.
If you are a landscape photographer you might not care, unless you are scaring away the birds.
The truth is USM is just one of those mostly useless "EXTRAS" lens manufacturers put into lenses so they can add a $100 extra to the price tag. So most lenses have them but for a lot of those lenses who cares.
