Lens question ?

[illuminati919]

Whats the big difference between a USM lens and regular lens ? The price of a USM lens seems to cost way more, why ??????

[DanielB]

Whats the big difference between a USM lens and regular lens ? The price of a USM lens seems to cost way more, why ??????
USM = faster more accurate autofocus system. small price to pay for not having backfocus issues in a football game.:D

personally when i'm shopping for a lense. i make sure it ALWAYS has USM. *personal preference*

-daniel-

[Red Bull]

USM is also much quieter while focusing. Also, if it's true ring USM, nothing on the barrel of the lens rotated while focusing.