VS.

[droyz2000]

Which lens motors are faster USM, SWM, or HSM? I have an SWM lens and think that the USM lenses are quicker but I could be wrong.

 

[keith204]

I've heard USM is a bit faster. However, HSM is plenty fast for me (shooting cars going over 100 mph) in AI-Servo.

 

[Big Mike]

The actual speed at which the lens focuses, is determined by several factors. The AF sensor system for one...which resides in the camera and is better on higher end cameras. Then there is the lens design. A bigger, heavier lens may be slower. The actual distance that the lens elements has to move, may be different from lens to lens.

Also, some lenses (high end telephoto) have focus limiter switches. Which helps to focus faster in some situations.