Hi,
I would like to ask if these below lenses have AF/MF switch. Can it AF when used on Canon 350D?

Sigma:
70-300mm F4-5.6 DG MACRO
70-300mm APO DG MACRO

Tamron:
AF70-300mm F/4-5.6 Di LD Macro 1:2


Does the AF in front of the Tamron lense represent auto focus?