check out the MTF charts @ photozone.de
ddr 發表於 2011-6-19 10:14 AM
sure! lets try all the worst circumstances
Tamron 18-270(test with 60D) - Canon 18-200 EF-S(test with 60D) - Nikon 18-200 DX(test with D7000)
barrel distortion at 18mm: (smaller number better)
T -3.88% - C -4.48% - N -4.13%
Canon loses
vignetting at 18mm: (smaller number better)
T 1,02 - C 1,48 - N 1,19
Canon loses
MTF (borders) at 18mm: (bigger number better)
T 1757 - C 1703 - N 1932
Canon loses
MTF (borders) at 200mm: (bigger number better)
T 1503 - C 1597 - N 2025
Tamron loses but can go further to 270mm...
Chromatic Aberrations (smaller number better)
at 18mm f3.5:
T 1.6 - C 1.28 - N 1.48
at 200mm f5-5.6
T 2.82 - C 2.45 - N 2.11
Tamron loses in across the board with CA~
which is not a big deal when it's pretty even across the board.
their verdict: "All-in-all the lens may be a tad better than Canon's 18-200mm f/3.5-5.6 IS..."
overall, Tamron is a winner, although not by much, but very comparable to similar offerings from Nikon and Canon, and it has the added advantage of 201-270mm range that neither Nikon nor Canon can match.
not sure, i bought my non-PZD version in Cam2. picked 3 before settle on a good one. always check lens thoroughly before buying. esp. 3rd party lens have lots of QC problems.
發表於 2011-6-12 12:12 AM
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