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Tamron AF 55-200mm Di II LD Macro Review - III Optical Performance55mmAll these images are 100% crops from large/fine JPEGs shot using a Canon EOS 20D. At 55mm comparison shots were made with a EF-S 18-55/3.5-5.6. The first set of images shows performance in the center of the frame.
As you can see there isn't a lot of difference between these two lenses in the center of the frame. The Tamron is a stop faster of course and does show a little increase in sharpness when stopped down to f5.6. Below are crops taken from the top left corner of the frame.
Here it's pretty clear that the Tamron does better than the Canon lens, even wide open at f4. It does sharpen up when stopped down from f4 to f5.6, but even at f4 it's better than the Canon lens stopped down to f8. As I said in an earlier review of the EF-S 18-55, corner performance wide open at 55mm isn't it's strong point!
100mmAt 100mm I used a Canon EF70-300/4-5.6 IS lens for comparison. This is a much more expensive lens ($560), but since it's the curently only zoom I have that covers 70-200mm, it's what I used! Note that it has an SD glass element and it is not the same optically as the cheaper 75-300/4-5.6 lenses.
In the center of the frame the Tamron lens isn't quite as sharp as the Canon when used wide open, but does improve a little when stopped down. Overall sharpness is pretty good in the center of the frame.
At the corner of the frame, especially wide open, the Tamron is a little soft. It doesn't really sharpen up fully until stopped down to f8. I ran a couple of tests on other targets to double check this and I found similar behavior 200mm
At 200mm center sharpness is pretty good. Not quite up to the image quality of the more expensive Canon lens, but certainly very acceptable.
At the corners, you can see some chromatic aberration in the Tamron lens shots. They're also not quite as sharp as the shots from the Canon EF 70-300/4-5.6 IS, but again I'll remind you that the Canon lens is $560 and the Tamron lens is closer to $180. • NEXT - Part IV - Flare, Distortion, Macro and Conclusions
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