My question has to do with the USM motor of the two lenses. Both
are fast (pretty equal), but the 50/1.4 makes some noise while the
28-135 is absolutely quiet. Is this normal?
JCDoss
Yes, it's normal.
The 50 1.4 uses the micro-motor type, while the 28-135 is the ring
motor type. You can read about them at the Canon USA EF lens site.
I think if you click on the USM symbol in the lens listings you get
a window with the details. (Technically the ring motor should
focus faster but that 1.4 speed makes up for a lot!)
See you,
--
Dave Werner