Canon USM

[Tom]

Archived from groups: rec.photo.digital (More info?)

Is Canon's USM focusing (?Ultra sonic motor?) an improvment over the
"other" types (DC?)? Does it make a difference to the average
photographer?

Thanks

Tom

 

[Guest]

Archived from groups: rec.photo.digital (More info?)

"Tom" <tbgibb@aol.com> wrote in message
news:1109136022.144511.277790@f14g2000cwb.googlegroups.com...
> Is Canon's USM focusing (?Ultra sonic motor?) an improvment over the
> "other" types (DC?)? Does it make a difference to the average
> photographer?
>
> Thanks
>
> Tom
>
Short answer: Yes. Slightly longer answer: USM is faster than non USM.
Ring USM is faster and quieter than micromotor USM, Sigma's HSM or the
standard focusing motors in Canon and other lenses. Ring USM, which is the
true USM, is distinguished by full time manual and a non rotating front
element. The only micromotor lens that has FTM and a non rotating front
element is the Canon 50mm f1.4 USM. And it ain't quiet, neither. ;-)

--
Skip Middleton
http/www.shadowcatcherimagery.com