Upload & Sell: Off
For those of you who still can't face the facts here are some clips from reviews. The optical perfomance charts support these quotes as well. Let's examine the 70-200 f/2.8 lenses to start:
Tamron 70-200 f/2.8 Di LD-
"Because of the inconsistent AF accuracy, I'm withholding recommendation of this lens for time-critical work. If you can shoot, check the results and reshoot if necessary (as many times as necessary), this lens can deliver very nice results for a relatively small cost. I would be very uncomfortable if I had to use this lens for a wedding - or adding the slow AF speed factor, for action sports - or for any other important shot that I couldn't reshoot.
If your tolerance level for OOF (Out of Focus) shots is higher than your budget, this might be the right lens for you. ", Bryan Carnathan
Canon 70-200 L 2.8 IS v2 -
"The Canon EF 70-200mm f/2.8 L IS II USM Lens delivers impressive image quality, focuses accurately very fast and has top-of-the-line build quality, 4-stop Image Stabilization, weather sealing and a very useful focal length range. " and "I consider the Canon EF 70-200mm f/2.8 L IS II USM Lens to be the second most important lens in my kit with the first being a more general purpose lens in focal length range. It is not an inexpensive lens, but it is very worth the price in my opinion - and very worthy of its red ring. While this is a completely pro-grade lens, you definitely do not have to be a pro to appreciate it. Get the "II"! " Bryan C as well.
Sigma 70-200 2.8 EX
-DPReview doesn't allow for reprinting of their results but to paraphrase them they say it's a good lens when used within it's design limitations which are significant.
Now I've posted a little comparison how about you guys try to refute... unless your lenses really aren't as good as you think...
For those of you who like the Sigma, most of the reviews out there recommend the Tamron over the Sigma for second party lenses.