Through the ISO-12233 sample image, I thought 'EF 70-300 IS USM' is much more blur than A005 at 300mm. The mid frame and corner is very worse than A005, and the center is very similar.


http://www.the-digital-picture.com/R...mp=4&APIComp=0

But the review said that:
"By 300mm, this lens delivers poor image quality across the frame (except on the far left side of the frame). Stopping down at 300mm helps, but even f/11 image quality is only marginal. If you consider this a 70-200mm lens, you will be more happy than if you are counting on getting great 300mm image quality. "
"The Canon lens most comparable to the Tamron 70-300mm f/4-5.6 Di VC USD Lens is the Canon EF 70-300mm f/4-5.6 IS USM Lens. The Canon's advantages include modestly lighter weight, better AF accuracy, less vignetting and less pincushion distortion through 200mm."

http://www.the-digital-picture.com/R...ns-Review.aspx

I have been confused, anyone can help me to understand that?