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Miljenko Devcic | profile | all galleries >> tech >> Lens reviews and tests >> Sigma 17-70 vs Sigma 18-50 tree view | thumbnails | slideshow

Sigma 17-70 vs Sigma 18-50

Sigma 17-70mm f2.8-4.5DC is modestly priced compared to established 18-50mm f2.8DC lens from their EX series. Does it makes sense to compare two lenses positioned into different categories? According to results, it does! Check 100% crops extracted from full size pics shot with Nikon D200 at 19, 24, 28, 35 and 50 mm. At 19 mm Sigma 18-50 is set to 18mm mark, but actual focal length is 19mm. This time I am not publishing Imatest resolution charts. The reasons are poor edge results due to curved focal plane. Real life pics (like those presented in above crops) tell the story more realistic and accurate for those two lenses. Please check Excel charts where light fall-off and distortion was measured for both lenses. Besides pics and charts, here are brief findings: on average, both lenses are roughly equal in sharpness. 18-50 excells at wide end, while 17-70 takes over at 35mm and above. 17-70 has better contrast and is neutral in colour, compared to 18-50 that has slight yellow cast. For most comparisons 18-50 pics were trimmed by +0.3 f-stops, while 17-70 pics were lowered by -0.7 f-stops.
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Temporary resolution chart
Temporary resolution chart
Light fall-off
Light fall-off
Distortion
Distortion
Sample variation
:: Sample variation ::
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