The 20mm F2 DG DN is a full-frame premium compact prime from Sigma’s I series range. Designed specifically for mirrorless cameras, it features an ultra-wide-angle focal length that is ideal for landscapes, weddings, interiors and astro. Owing to its advanced optical design, which includes three glass-moulded aspherical elements, one SLD element, one FLD element, and nano-porous coatings, the lens delivers exceptional image quality across the frame with very minimal chromatic aberration and well-controlled coma flare.
As with Sigma’s other I series lenses, the 20mm F2 combines superb optical performance with outstanding build quality and retro styling. Its sleek, all-metal body includes a metal focus ring, a metal aperture ring, a metal lens hood, and even a metal lens cap that attaches to the lens magnetically. The lens is essentially designed for photographers and film-makers who value the experience of taking a picture just as much as the quality of the final result.
Weighing less than 400g, the 20mm F2 is portable enough to be carried around for casual day-to-day shooting, but thanks to its outstanding optics, wide F2 aperture, fast AF and impressive build, is equally well-suited to heavy professional use.
Despite having a premium all-metal build comprising precision-cut aluminium parts, the 20mm F2 weighs only 370g (L-Mount), making it perfect for landscape and travel photographers who prefer a compact but robust lens that can easily be carried around all day. The lens has a dust- and splash-proof mount and an aperture ring.
The tactile knurled metal finish used for the lens hood, focus ring and aperture ring make controlling settings and gripping the lens a joy to use. Included with the lens is a magnetic metal lens cap in addition to the regular plastic cap, which further improves ease of use. Unlike some ultra-wide-angle optics, the lens features a 62mm filer thread that makes it easy to attach ND filters, ND grad filters and polarisers, ideal for landscape photography.
Metal mount with seal
Protects against dust and moisture.
Including metal aperture and focus rings.
Despite its size, the 20mm F2 DG DN delivers outstanding optical quality across the whole frame, even on ultra-high-resolution sensors. Owing to its advanced optical design, which includes 13 elements in 11 groups, results remain pin-sharp, even when shooting at the widest aperture of F2. Important for a wide-angle lens, optical performance is maintained across the whole frame, meaning fine detail is perfectly captured right into the corners.
Chromatic aberration is very well-controlled around areas of high contrast, and vignetting is minimal even wide-open. The lens has advanced optical coatings which reduce flare and ghosting when working in bright direct sunlight.
A bright F2 aperture allows plenty of light through the lens, which is particularly useful in low-light shooting situations. For astrophotographers, it ensures excellent star detail in shorter exposures, and for photographers using the lens hand-held in low-light its helps eliminate camera-shake.
A fast aperture also means a shallow depth-of-field for blurry backgrounds. This allows photographers to isolate their subject and create more impactful images.
The 20mm F2 DG DN | Contemporary is considerably smaller and lighter than the 20mm F1.4 DG DN | Art, and delivers comparable image quality, so will appeal to those who need uncompromising optical performance while needing to work light. However, the 20mm F1.4 DG DN | Art does offer a wider F1.4 aperture and more advanced features.
Available as a separate accessory Sigma’s innovative magnetic lens cap holder can be clipped to clothing or a bag to securely hold any I series magnetic lens cap. This helps keep the cap safe while the camera is in use.
The lens is part of the I series range of primes, which sit in the Contemporary line-up. They are designed to offer mirrorless photographers outstanding optical quality and premium usability in a compact package.
With similar optical character and the same sleek external design, the lenses are ideally used as a set, ensuring consistent bokeh, colour rendition, optical precision and usability.
All Sigma cameras and lenses are designed, manufactured and assembled at our sole factory at Aizu in Japan. This domestic production model is unusual in today’s industry, with most imaging companies opting to outsource to other countries to reduce costs. But SIGMA believes that keeping virtually all manufacturing, processing and assembly in Aizu is essential for creating innovative, carefully thought-out and impeccably constructed products that meet the high standards demanded by professional photographers and film-makers around the world.
Sigma chose Aizu as its main production base in the early 1970s. Situated at the base of Mount Bandai in the Fukushima Prefecture, about four hours’ drive north of Tokyo, Aizu has an abundance of very clean water from mountain streams, which is essential for grinding and polishing lenses. Sigma’s founder, Michihiro Yamaki, was also drawn to this area for its workforce, who have a reputation for their craftsmanship, work ethic and attention to detail. Mr Yamaki’s son, Kazuto Yamaki, now the owner and CEO of SIGMA Corporation, has the same unwavering commitment to keeping production in Japan.
Today Sigma’s factory is more than 50,000 square feet in size, and packed full of some of the most advanced optical manufacturing technology in existence. So when you buy a Sigma camera or lens you can be sure that virtually every single component part has been manufactured and assembled by SIGMA, in Japan, with the greatest level of care and attention. We hope you enjoy using our products.
If you want to see how a particular SIGMA lens or camera performs, why not test drive it with our SIGMA Select hire service. Available for selected SIGMA lenses, short-term loans are free of charge (including shipping), with a small fee if you want to test it for longer. Refundable deposit required. Subject to availability.
13 elements in 11 groups
Angle of view
Number of diaphragm blades
9 (rounded diaphragm)
Minimum focusing distance
Maximum magnification ratio
Dimensions (diameter x length)
ø70mm × 72.4mm
Corresponding AF mounts
L-Mount | Sony E
Sony E barcode
Specifications are for L-Mount
A special coating applied to the front element to help repel water and oil.
This suppresses flare and ghosting by minimising reflections within the lens, ensuring punchy, high-contrast results. All lenses in the current Sigma range feature this technology.
The magnetic lens cap comes boxes with all I series lenses (except the 45mm F2.8), in addition to the standard plastic cap. It attaches to the lens magnetically.
Internal focus or an inner focus system means the lens configuration uses movable internal lens elements that adjust focus without changing the length of the lens barrel. This helps keep the centre of gravity of the lens more constant when changing focus.
The lens has an image circle large enough to be used on a full-frame camera. It can also be used on cameras with a smaller ‘crop’ sensor, provided the mount is compatible.
The lens has a filter thread around the front element onto which filters and filter holders can be attached.
The mount is the part of the lens that attaches to the camera body. A coated brass mount is used for strength, and is surrounded by a rubber seal to keep out dust and moisture.
This switch toggles between autofocus and manual focus.
The diaphragm is constructed of nine rounded blades for a circular aperture opening and round out-of-focus highlights.