Sigma 50-200mm f/4-5.6 DC OS HSM - £179/ $159
There are many similarities between this Sigma and the Nikon 55-200mm VR. Both are designed exclusively for DX-format Nikons and are almost identical in size, though the Sigma is a little heavier. They also both feature basic (rather than ring-type) ultrasonic autofocus and have internal focusing with non-rotating front elements. The Sigma's OS (Optical Stabiliser) is rated at four stops rather than three, but the effectiveness was the same in our tests.
Notable differences include the Sigma having a metal mounting plate rather than a plastic one, and the lens features a focus distance scale that's lacking on Nikon's 55-200mm VR and 55-300mm VR models. The focus ring is also easier to use for manual focusing. However, because the ring rotates during autofocus, it's easier to foul its action with your fingers when holding the lens.
In terms of sharpness, optical quality is the opposite of that of Nikon's competing 55-200mm VR lens. The Sigma optic is more typical of telephoto zooms, delivering its sharpest images at shorter and mid-range focal lengths. At the maximum available aperture of f/5.6 and 200mm setting, the sharpness drops off considerably.
Lab test results
Overall, the Sigma's 50-200mm centre sharpness is the lowest, not helped by its disappointing result at 200mm.
At 50mm and 135mm, colour fringing is low, and there is only a faint sign of a blue edge at 200mm.
There are signs of barrel distortion at 50mm. At 200mm, pinch distortion is the most visible in the test.
Image quality verdict
Levels of sharpness and colour fringing are average, but the level of distortion – from barrel to pinch – proved to be the highest in the test.
Read the full Sigma 50-200mm f/4-5.6 DC OS HSM review