Canon EF-S 17-85mm purple fringing comparison
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To measure purple fringing caused
by lens chromatic aberrations and sensor blooming, we photographed a
test chart, left, with areas of very high contrast. We tested each lens
at its widest and longest focal lengths with the aperture wide open using
a Canon EOS-350D / Digital Rebel XT in Aperture Priority mode. The crops
are taken from the upper left corner of the chart and presented here at
100%.
The three lenses performed roughly the same in this test throughout their
focal lengths, although the 18-55mm exhibited slightly worse fringing at
wide angle. |
Canon EF-S 17-85mm f4~5.6 IS USM |
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Canon EF-S 18-55mm f3.5~5.6 |
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Canon EF 17-40mm f4.0L USM |
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17-85mm EF-S at 17mm f4.0 |
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18-55mm EF-S at 18mm f3.5 |
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17-40mm EF L at 17mm f4 |
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17-85mm EF-S at 85mm f5.6 |
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18-55mm EF-S at 55mm f5.6 |
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17-40mm EF L at 40mm f4 |
Canon EF-S 17-85mm macro comparison
To measure macro performance we photographed a custom chart using settings
which delivered the maximum possible reproduction. The dark lines are 10mm
apart. Each lens was tested with the Canon EOS-350D / Digital Rebel XT at
f8 in Aperture Priority mode.
The three lenses delivered quite different macro performance, with the 17-85mm
EF-S delivering the least reproduction with a maximum area of 104x70mm. The
17-40mm EF L did a little better, but surprisingly the 18-55mm EF-S performed
best of all in this respect with a reproduction around one and a half times
greater than the 17-85mm EF-S. |
Canon EF-S 17-85mm f4~5.6 IS USM |
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Canon EF-S 18-55mm f3.5~5.6 |
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Canon EF 17-40mm f4.0L USM |
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17-85mm EF-S at 85mm f8
Max area of 104x70mm |
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18-55mm EF-S at 55mm f8
Max area of 66x44mm |
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17-40mm EF L at 40mm f8
Max area of 92x62mm |
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