Sigma 17-70mm f/2.8-4 DC Macro OS HSM | C

Equiv. focal length (DX): 25.5-105mm internal zoom/focus: No/yes Elements/groups: 16/14 Diaphragm: 7 blades optical stabilizer: 4-stops focus type: Ultrasonic (motor) min focus Distance: 0.22m max reproduction ratio: 0.36x filter size: 72mm Diameter X min length: 79x82mm Weight: 465g price: £349/$499

Sigma also makes a DX format 17-50mm standard zoom with a constant f/2.8 aperture rating, this time with optical stabilization. But, the newer 17-70mm lens is smaller, lighter and has better all-round performance and image quality, again with stabilization.

This lens is specifically designed to keep size and weight to a minimum. Even so, it’s only 15g lighter than the Nikon, despite having less zoom range, and is almost the same size. The optics include two top-grade FLD (‘Fluorite’ Low Dispersion) elements.

With its motor-based ultrasonic autofocus system, the Sigma isn’t as quick or quiet. The focus ring rotates during autofocus and full-time manual override is unavailable. One plus is a shorter minimum focus distance and greater max magnification ratio.

The Sigma has better sharpness than the Nikon at its longest zoom setting and performs well with the rest of the zoom range at apertures of f/5.6 or narrower. Image quality is a bit better than the Nikon in terms of colour fringing, distortions and vignetting.

The Sigma lens feels well engineered and delivers similar image quality to the Nikon, while its close-focusing ‘macro’ facility is a bonus, as is the option of fine-tuning the lens with Sigma’s optional USB Dock. At the price, it’s exceptional value for money.