Photography News issue 28

Photography News Issue 28 absolutephoto.com

47

First tests

Sigma 20mm f/1.4 DG HSMA £799

Specs

Format Full-frame and APS-C Mount Canon, Nikon, Sigma and Sony Construction 15 elements in 11 groups Special lens elements 2 aspherical, 5 SLD, 2 FLD glass Coatings Sigma Super Multi Layer Filter size Not applicable Aperture range f/1.4-16 Diaphragm 9 blades Internal focus Yes Manual focus Full-time manual override, AF with Hyper Sonic Motor Minimum focus 27.6cm Focus limiter No Maximummagnification 1:7.1 Distance scale Yes Depth-of-field scale No Image stabiliser No Tripod collar No Lens hood Built-in Weather-sealed No Dimensions (lxd) 90.7x129.8mm Weight 950g Contact sigma-imaging-uk.com

Sigma has a great reputation for its high-quality lenses, but it has upped its game in recent times with its Art range, most notably the 50mm f/1.4 DGHSMA. The 20mm f/1.4 DGHSM A is the latest lens in the range and a very impressive one it is. It’s also the first-ever full-frame, 20mm with this super-fast wide aperture. It is certainly imposing physically but balanced nicely on our test camera, the Nikon D800, and despite its short focal length, it looks like a telephoto in size. Engineering quality and finish are first-rate and it looks and feels fabulous. The bulbous front element and the permanent petal lens hoodmeans that using screw-in filters is not an option. Keen filter users will have towait until Lee develops an adapter ring for its SW150 system. The broad focus barrel features full-time manual focus override and takes you from infinity to the 27.6cm minimum focusing distance in about one-quarter of a turn. There is an AF/ manual focus switch too, but that’s the only control on this optic so there’s no image stabilisation. The short focus throw and internal focusing system really make for fast AF, assisted in no short measure by the lens’s HSM system. Sigma’s Hyper Sonic Motor technology has been around for a few years now and in this lens you can see why it is so highly thought of. Infinity to minimum focus is achieved in a fraction of a second and with great accuracy too. Of course, the lens’s short focal length means extensive depth-of-field even at mid apertures, but critical focus is important especially when you’re shooting close subjects. Optically, the lens is no let-down. Using a magnified live view image and manual focus with the camera mounted onto a tripod and released

The first ever full- frame, 20mm with

the super-fast wide aperture

with the exposure delay mode showed that the lens was excellent at maximum aperture. Wide open sharpness is very good in the centre of the frame with the edges being slightly less impressive but still good. It is only in the extreme corners where sharpness tails off, but essentially this wide-angle is perfectly useable at its maximum aperture for high-quality images. Stopping down improves overall quality and by f/2.8 fine detail across the image frame is very well resolved. F/4 produced even better quality, but the highest level of performance is achieved at f/5.6, where even in the far corners detail is very crisp with plenty of contrast. This high level is maintained at f/8 and then starts to tail away from f/11, although it is true that this isn’t too major and the smallest apertures can be used with confidence when maximum depth-of- field is needed. Vignetting is evident with the lens wide open and the corners are very clearly much darker than the centre. This is lessened a little at f/2, but you need to stop down to f/4 to get an evenly lit image. Barrel distortion, common with wide-angles, is present but not terrible and easily corrected in post-processing. There are signs of chromatic aberration but levels are low and again readily resolved in software. WC

Above Sharpness is very good in the centre of the frame at f/1.4. It tails off in the far corners, but overall this Sigma gives consistent high quality.

F/1.4

F/2

F/2.8

F/4

F/5.6

F/8

F/11

F/16

Verdict

The Sigma 20mm f/1.4 DG HSM A is a classy lens and totally deserves to be part of Sigma’s premium lens collection. It’s a fast ultra-wide lens than can be used at every aperture, confident in the knowledge that you get very sharp, high-contrast images. Its downsides are few and what you would expect with a fast, wide lens – it is heavy and filter use isn’t straightforward. These pale when its benefits are considered and for under £800, it is very good value for money.

Features Fast aperture, HSM and lots of exotic glass

23/25

22/25

Performance Impressive, especially at the centre of the frame

Handling Good despite being a bulky lens

21/25

Value for money There is no direct competitor from Canon or Nikon

23/25

89/100

Overall A bulky wide lens but the very fast maximum aperture gives it a strong appeal Pros AF speed, optical performance, very useable at f/1.4, good balance on a full-frame DSLR, short focus throw Cons Heavy, big, filter use an issue, not weather-proofed

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