HSM/USM

[LateModelSedan]

are these terms interchangeable? was looking at the new sigma 50mm 1.4 but AF only works with camera bodies that support HSM. if this is the same as USM then no problem. anyone know?

 

[reconstyle]

I would assume that they are the same thing.

USM = Ultra-sonic motor

HSM = Hyper-sonic motor - This lens uses a motor driven by ultrasonic waves to provide a quiet, highspeed AF.

 

[Big Mike]

Yes, they are pretty much the same thing. Although, I think that Canon 'ring' USM is still better (faster & quieter).

As long as you get a lens that is made for your camera brand/type...it will work. So if you have any Canon EOS camera, you need to buy the Sigma lens that is specifically for Canon EOS (or Canon EF or autofocus)...and not the on for Nikon, for example.