I got myself this lens as a replacement for my Canon 70-300IS and possibly backup for the 70-300 L IS.
After extensive testing the lens leaves very mixed feelings in me.
++ Resolution / sharpness. Enough in fact very close to the 70-300 L IS Ran and is especially at the edge definitely better than the Canon 70-300 (non L) IS.
++ Processing. It fits comfortably in your hand. The zoom mechanism is easy enough for a quick operation and tight enough that it is not below adjusts the focal length for tilt up / self. The lens is flush and has no play (no wobbles).
+ It is very quiet in operation (focus + stabilizer). Not quite as quiet as the Canon L, but no such Rappelkiste as the stabilizer from Canon non L.
- Auto Focus: On the one hand is relatively slow, the other in certain situations do not fail. I had a motive, in which I got even with 20 pictures a truly sharp result. These were a leafless tree against a blue sky. The sun, I had almost in the back. The Canon without L had so little trouble (about 30% out of focus) and the L-variant practically no problem with that.
- Exposure: I had about 1/3 stop Overexposure compared with the two Canons with my copy.
- Bokeh: Bokeh has clearly pronounced edges with negative consequences associated with the image stabilizer.
++ / - (Yeah right, both extremes at once) The image stabilizer! On the one hand really tack-sharp images, even at 1/50 second (++). On the other hand the stability produced in conjunction with the bokeh even at 1/1000 second in the blurred areas double edge (-)! The best visible when bright in (blurred) background, narrow strips (eg birch twigs) are.
Addendum 02.04.2011: Have a better understanding set two clients images that make the differences between the Canon (non L) and the Tamron hopefully clear!
My Conclusion:
I will return my Tamron again. Actually, I wanted to take it on the road. But I owe snapshots on the stabilizer, may leave the focus and free storage facilities (soft background) ... and in this total package weakened my copy ... at least in certain situations that may occur rarely, but I travel also can not be avoided.
I'll keep my Canon 70-300 IS. The images thus are indeed only in the center similarly sharp as the Tamron, but I get a more reliable yield of usable images.
Finally, I would stress once again that the problems only in certain situations. That with the auto focus and the troubled background must find out every man for himself. Who can live with it receives a lens having an approximately L-sharpness. Who wants to have the focus and a soft bokeh, which should save on the Canon 70-300 L ...
