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Tamron 18-200mm geometry, wide angle, tested with Nikon D2X
| To measure geometric distortion we photographed a test chart consisting
of a grid pattern with perfectly straight lines. The lenses were tested
at their widest focal length with an aperture of f8 using a Nikon D2X in
Aperture Priority mode. The images were analysed with Imatest using 5th
Order line calculation and the full areas presented here at a reduced resolution. All three lenses exhibited roughly the same degree of barrel distortion at their wide angle setting, although the Sigma model managed the best result here. |
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Tamron AF18-200mm F3.5-6.3 XR Di-II LD IF
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Nikkor AF-S DX VR 18-200mm 3.5-5.6G IF-ED
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Sigma 18-200mm F3.5-6.3 DC
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| 18-200mm at 18mm f8 Distortion: 5.38% barrel |
18-200mm at 18mm f8 Distortion: 5.26% barrel |
18-200mm at 18mm f8 Distortion: 4.46% barrel |
Tamron 18-200mm geometry, telephoto, tested with Nikon D2X
| To measure geometric distortion we photographed a test chart consisting
of a grid pattern with perfectly straight lines. The lenses were tested
at their longest focal length with an aperture of f8 using a Nikon D2X in
Aperture Priority mode. The images were analysed with Imatest using 5th
Order line calculation and the full areas presented here at a reduced resolution. All three lenses exhibited roughly the same degree of pincushion distortion when zoomed-into 200mm, although in contrast to the wide-angle result, the Sigma scored worst here, with the Tamron taking a fractional lead. |
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Tamron AF18-200mm F3.5-6.3 XR Di-II LD IF
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Nikkor AF-S DX VR 18-200mm 3.5-5.6G IF-ED
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Sigma 18-200mm F3.5-6.3 DC
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| 18-200mm at 200mm f8 Distortion: 1.19% pincushion |
18-200mm at 200mm f8 Distortion: 1.22% pincushion |
18-200mm at 200mm f8 Distortion: 1.76% pincushion |
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