Tamron to Canon 70-300 IS USM

[matt_wright]

Guys I'm thinking of upgrading my Tamron 70-300 to the Canon 70-300 IS USM (as an interim measure until I can afford L glass).
Obviously the IS and USM will be a great upgrade, but does anyone have any opinions on the sharpness and overall IQ.

Would be great to hear your opinions, I’m sure many people must have made this change, as Jessops always seem to be trying to flog the Tamron lens to first time Dslr buyers!

Matt

 

[Dave Stone]

I had one before I got the 100-400. It is a superb lens, you will love it if you get one.

 

[J4MIE_P]

Could I ask about the quality of the 100-400?
I can't seem to chose over the 70-200 F4
or the 100-400 F4-5.6
Surely the 100-400 is really slow with the f numbers being so high?