Smart_Photography_-_January_2016_

S

igma’s interchangeable lenses

are divided into three product

categories – Contemporary, Art

and Sports. Art lenses are designed for

the ultimate in optical performance and

can stand up to (and even go beyond)

the best lenses from leading camera

manufacturers. According to Sigma, the

Sigma 20mm f/1.4 DG HSM ART is the

world’s �irst ultra-wide-angle lens for

full-frame cameras offering a fast f/1.4

aperture. The lens is made in Japan and

is available in Sigma, Canon and Nikon

mounts. The lens that we received for

review had a Canon mount.

Design & Build Quality

Elegantly designed and beautifully

�inished in black, the Sigma 20mm

f/1.4 is a ‘pro’ lens for 35mm full-frame

format. When used on an APS-C camera

body, it will provide an equivalent focal

length of 32mm. The internal parts

employ the use of Thermally Stable

Composite (TSC) and metal which

ensure precise operation.

The lens mount is made of brass. The

lens barrel is engraved with the year

of release and the letter ‘A’ next to the

distance scale identi�ies the lens as an

‘Art’ lens. A raised white dot helps to

align the lens to the camera body. The

lens hood is an integral part of the lens.

The lens weighs 950g including both the

end caps.

Key Features

The Sigma 20mm f/1.4 DG HSM Art is

the world’s �irst 20mm f/1.4 lens. This

necessitates the use of a very large

distortion-free front element and Sigma

was able to achieve this breakthrough

due to their advanced large-diameter

aspherical lens manufacturing

technologies. Generally, ultra-wide-angle

lenses with large maximum aperture

suffer from chromatic aberrations.

To combat this problem, the Sigma

20mm f/1.4 is constructed with 15

elements in 11 groups that include 2

FLD (F-Low Dispersion), 5 SLD (Special

Low Dispersion) and 2 aspherical

lens elements which signi�icantly

reduce these aberrations. Super multi-

coating on key elements reduce �lare

and ghosting. Not only that, Sigma’s

advanced optical design helps to reduce

corner darkening and minimize various

other types of distortion.

A Hyper Sonic Motor (HSM) aids in

quick and ef�icient autofocussing.

Manual overriding of AF is possible by

merely turning the focus ring. There is

no need to use the AF/MF focus switch,

thus allowing faster �ine-tuning when

necessary. A distance scale in feet and

meters and a depth of �ield scale for f/8

and f/16 is available, though this would

be dif�icult to see in low light. Due to

the bulging front element, �ilters cannot

be used. Since the lens has internal

focussing, its dimensions remain the

same during focussing.

Ergonomics

We tested the lens on a Canon EOS 6D

body. Though reasonably heavy (935g

without end caps), the combo balanced

Sigma Does It Again!

well. The lens was very easy to use.

Performance

Overall, the Sigma 20mm f/1.4 DG

HSM Art performed very well. Used

wide open at f/1.4, centre sharpness

was good while the corners and the

sides were de�initely much softer.

In all fairness, this would happen

with almost all ultra- wide-angle

fast lenses. Stopping down the lens

improved the sharpness at the centre

as well as the sides. F/4 appeared to

be the sharpest at the centre, closely

followed by f/5.6. F/5.6 appeared to

be the sharpest at the corners. By f/16,

images were noticeably softer (centre

as well as corners) due to diffraction

of light. F/11 too showed some signs

of softening.

Distortion control was superb –

almost imperceptible barrel distortion

was noticed and that too at very close

distances. I would happily use this lens

even for architectural photography!

Sigma 20mm f/1.4

DG HSM ART^ `^ 73,000 Rohinton Mehta

✓ Lens

✓ Lens pouch

✓ Front & Rear lens caps

✓ Instruction lea�let

Inside the Box

LENS

REVIEW

106

Smart PhotographyJanuary 2016

http://www.smartphotography.in