![]() ![]() After this point, the corners show pincushion distortion while the central region shows some slight barrel distortion. Between 50-67mm, distortion is slightly barrelled, at +0.4% in the corners the lens reaches a kind of parity around 62mm. At any other focal length and aperture setting, corner shading is negligible.ĭistortion results for the Sigma 50-200mm ƒ/4-5.6 are typical for this class of lens, showing a complicated mix of both barrel and pincushion distortion in the longer range of its telephoto focal length. It's at its worst at 50mm at other apertures, it's actually fairly good.Ĭorner shading isn't much of a factor for this lens, with only a 1/3-EV difference between the corners and the center when used wide open at any focal length. It's not bad at ƒ/4, but at ƒ/8 and smaller it's particularly noticeable. Where the Sigma 50-200mm ƒ/4-5.6 OS offers fairly good results for sharpness at 50mm, CA is fairly notable. Stopping down to ƒ/8 tames the uneven-ness, but that's about as good as it gets - there's no additional improvement from stopping down further (~2-3 blur units).įully stopped-down performance is best avoided while relatively good at wide angle (~3 blur units at 50mm and ƒ/22), smaller apertures quickly degrade, until we note 5-6 blur units at 200mm and ƒ/32. At 200mm the lens is pushed to its limit, showing uneven focus when used wide open at ƒ/5.6, and performance ranging from 2 to 5 blur units across the frame. Stopping down helps here, and again, things even out around ƒ/8-ƒ/11 where the image shows between 1.5-2 blur units. Performance is similar up to and including 100mm: the right side is notably softer than the left, suggesting to us the lens is slightly de-centered.Ībove 100mm, the lens shows a nice sweet spot of sharpness in the near-center, but again, de-centering shows off a soft corner, the right, where we note almost 5 blur units at 135mm. By ƒ/8 the image is as sharp as it will get, still around 1.5 blur units. Stopping down only offers marginal improvements, most notably smoothing out the errant corner. ![]() Wide open at 50mm and ƒ/4, the lens does quite well at around 1.5 blur units, with one soft corner in the upper right hand side. The lens is respectably sharp between 50 and 100mm longer than this, and image sharpness drops off. The lens ships with a circular-shaped lens hood, takes 55mm filters, and is available now for approximately $300. ![]()
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