Sigma 50mm f/1.4 DG HSM | A

Elements/groups: 13/8 Diaphragm: 9 blades Optical stabilizer: No Focus type: Ultrasonic (ring-type) Min focus distance: 0.4m Max reproduction ratio: 0.18x Filter size: 77mm Accessories inc: Hood, soft case Size: 85x100mm weight: 815g Price: £570/$950

Much larger and more complex than Nikon’s AF-S 50mm f/1.4G lens, with 13 elements compared with eight, this hefty ‘Art’ class Sigma is twice the length and weighs 815g, compared with the Nikon’s 280g. Build quality is very good but it lacks weather-seals.

The Sigma has a classic f/1.4 aperture rating, generally preferred for getting a tight depth of field and blurring the background in portraiture. It’s particularly useful if you’re shooting fairly tight head-and-shoulders portraits with a DX-format body.

There’s no image stabilization in the Sigma lens, but it’s not a problem if you’re shooting at or near the widest aperture. Even indoors under ambient lighting, you can usually get a sufficiently fast shutter speed without bumping up the ISO too much.

The Sigma delivers very good sharpness across the frame at most apertures, only really dropping off at f/1.4, which the Tamron can’t match. Bokeh is very smooth, colour fringing is minimal and distortion is negligible. Image quality is excellent in every respect.

Compared with Nikon’s comparatively basic AF-S 50mm f/1.4G (£415/$450), the Sigma is good value in the UK, at £570. However, it’s much more pricey in the USA, at $950, making it relatively poorer value for money.