In summary
An ultra-wide angle zoom lens with minimal distortion, a constant f/4 maximum aperture and improved autofocusing.
Buyers of this lens can expect sharp images at the optimal focal length and aperture settings. The lens also handles flare and backlighting remarkably well and is barely affected by distortion and vignetting for the angles of view it covers. Any shortcomings that occur are mainly with focal lengths of 20mm and 24mm, which can be overcome by swapping to a lens that covers these angles of view.
This lens is of particular interest because there aren’t many full-frame-compatible, ultra-wide-angle rectilinear (non-fisheye) zoom DSLR lenses to choose from.
Full review
Sigma unveiled its third generation wide-angle zoom lens, the 12-24mm f/4 DG HSM Art lens, on 16 September, just before Photokina 2016. A significant update to the 12-24mm f/4.5-5.6 HSM DG II model, it comes with Canon EF, Nikon F (FX) and Sigma SA mounts. Like its predecessor, while designed primarily for ‘full frame’ cameras, it can be used on cameras with APS-C sized sensors, where it covers the equivalent of an 18-36mm lens on Nikon cameras with a 1.5x crop factor or 19.2-38.4mm on 1.6x crop Canon DSLRs.
The new Sigma 12-24mm f/4 DG HSM Art lens. (Source: Sigma.)
The optical design of this lens is quite complex, with 16 elements in 11 groups. Among them are two aspherical lenses (one an 80mm diameter moulded glass aspherical lens), one hybrid aspherical lens, five FLD glass elements with performance equal to fluorite lenses and a special low dispersion (SLD) lens. Their positions are shown in the optical diagram below.
Super Multi-Layer coating has been applied to certain elements to minimise ghosting and flare. A rounded nine-blade iris diaphragm creates attractive bokeh at wide aperture settings. This lens is part of the Art line within Sigma’s Global Vision series and fully compatible with Sigma’s USB Dock.
Who’s it For?
Wide-angle lenses are traditionally used for landscape and architectural photography and this Sigma lens will be particularly suitable for both since it has been designed to be almost distortion free. It could also be used for event photography, particularly when taking portraits of large groups of people in cramped situations.
At 1.15 kilograms, this is a large and heavy lens that is best suited to larger cameras. While it can be used on cropped-sensor DSLRs, we wouldn’t recommend it ““ even with larger models ““ because better alternatives are available. (Some are listed in the Conclusion section below.)
What’s New?
The main feature that distinguishes the new lens from its predecessor is the constant f/4 maximum aperture, which makes it significantly faster than the 12-24mm f/4.5-5.6 HSM DG II lens. Extra lens speed comes at a cost; more glass and larger elements must be used to capture more light and that means an increase in weight, in this case making the new lens 480 grams heavier than its predecessor.
At the same time, fewer lens elements have been used in the design, although they are larger and, naturally, heavier. The Mark II lens had 17 elements in 13 groups, among them four aspherical, four FLD and one SLD elements. It also used only six diaphragm blades, compared with nine in the new lens and more blades should produce smoother bokeh.
The new lens will also focus closer than its predecessor, going down to 24 cm at 24mm, whereas the older lens was limited to 28 cm. Both lenses share the same HSM (Hypersonic Motor) AF drive mechanism, which is fast and almost noiseless. And both have permanently-attached lens hoods that are petal-shaped.
Build and Ergonomics
Like its predecessor, the12-24mm f/4 DG HSM Art lens is solidly built, using a combination of metal and Thermally Stable Composite (TSC) plastic, which interfaces seamlessly with metal parts. Relatively heavy for a wide-angle zoom, it is made in Japan and features a brass bayonet mount.
For a premium lens, the weather sealing is limited, with a rubber gasket around the lens mount and water-repelling coating on both front and rear elements the only provisions. The overall assembly of the lens is tight, but outdoor photographers should be aware that moisture could penetrate if the lens gets wet.
The front element of the lens bulges forward, which means the lens hood has to be permanently attached to provide some degree of protection against impact as well as glare. No threading is provided for attaching a front-mounted filter and, unlike the previous 12-24mm f/4.5-5.6 HSM DG II lens, no provision is made for fitting filters via a gelatin filter slot at the rear of the lens.
The petal-shaped hood is about 30 mm deep at its widest points. A 34 mm deep, cup-shaped lens cap is supplied to cover the front of the lens when it isn’t in use. It fitted quite snugly on the review unit but was a bit too large to slip easily into a pocket while the lens was in use.
The focusing ring is located roughly 52 mm behind the front of the lens hood. It’s about 13 mm wide and almost totally covered by a ribbed rubber grip band. This ring turns through roughly 120 degrees and is linked to a distance scale which is inset into the lens barrel immediately behind the trailing edge of the focusing ring.
The lens steps down by about 8 mm at this point to form a 22 mm wide unmoving section of the barrel. The distance scale is at its leading edge and located behind a transparent plastic cover. It’s calibrated in metres and feet and covers distances from 0.24 metres to infinity.
Around the left hand side of this section of the barrel is the AF/MF switch, a simple slider on a raised section of the barrel. Between it and the distance scale is the silver circle with the A mark that identifies an Art lens. The base of this section of the barrel is ribbed to provide a secure and comfortable grip and the ribbing stretches from just below the AF/MF switch to two thirds of the way up the right hand side of the barrel to allow for the lens being used with vertical orientation.
The zoom ring is 20 mm wide and located just aft of the distance scale. Its 5 mm wide leading edge is stamped with markings for the 12mm, 14mm, 16mm, 18mm, 20mm and 24mm focal lengths, which are lined up against a white mark on the fixed section of the lens barrel, just in front of the focusing ring.
The remainder of the ring has a broader rubber ribbing encircling it. It turns through a little less than 90 degrees as you move from 12mm to 24mm with hard stops at each end of the range. At the same time, the front element of the lens moves forwards, although it doesn’t rotate.
The remainder of the barrel is about 15 mm long and gently curved as it segues inwards to the metal mount, which is surrounded by a rubber gasket. A white dot on the camera-side edge provides an index mark for fitting the lens to a camera body.
The lens is available with mounts to suit Canon EF, Nikon F (FX) and Sigma SA camera bodies. It is supplied with front and end caps plus a soft carrying pouch and one-year limited warranty.
Performance
A couple of things surprise you when you first look through the Sigma 12-24mm f/4 DG HSM Art lens. The first is how much it can encompass at the 12mm setting; the second is the comparatively small amount of distortion you can see. Although this can depend on whether you have in-camera distortion corrections enabled, even with cameras where such corrections aren’t provided, verticals and horizontals in the frame remain close to their true straightness.
Naturally, the way the lens ‘maps’ image points to the sensor impacts on how scenes are recorded (and perceived). With the 12mm setting, there’s an obvious spreading as the shorter edges of the frame are approached, making the characteristic wide-angle distortions very obvious. As a consequence, the first time you use the lens, you’re tempted to ‘play’ with the inherent distortions to see what can be done with different camera/subject angles and camera-subject distances within the frame. Examples are shown in the Samples section below.
Imatest showed the best performance was obtained at around f/5.6, which is a stop down from the maximum aperture and the highest resolution was obtained with the 14mm, 16mm and 18mm focal lengths. In each case, it exceeded expectations for the 21-megapixel resolution of the Canon EOS 5D Mark II camera we used for our tests.
Centre resolution was a little below expectations with the 12mm, 20mm and 24mm focal lengths, although pictures shot at f/5.6 with these focal lengths appeared to be quite sharp.
At f/4, centre resolution was shown to be lower and edge softening was significant. This remained true throughout most of the focal length and aperture ranges until about f/16, where diffraction had also begun to reduce centre resolution. The graph below shows the results of our Imatest tests across the aperture ranges for the six marked focal length settings.
Lateral chromatic aberration remained within the negligible band for all aperture and focal length settings, as shown in the graph of our Imatest results below, in which the red line marks the boundary between ‘negligible’ and ‘low’ CA. We found no evidence of coloured fringing in test shots taken with in-camera corrections disabled.
We found a rather odd pattern in our vignetting tests (which involved photographing a clear blue sky with the lens de-focused) at f/4. With shorter focal lengths, there was a dark area covering the centre of the frame. This area blended into the surrounding areas gradually as the focal length was increased, becoming completely integrated (and slightly lighter than the surrounding areas) at 24mm.
Corner darkening could be seen with all focal length settings, although it was remarkably low and well controlled for such a wide-angle lens. Stopping down to f/8 removed both the vignetting and the central darkening and produced relatively even lighting throughout the frame.
Attractive bokeh isn’t a common characteristic of ultra-wide-angle lenses and the Sigma 12-24mm f/4 DG HSM Art lens is no exception. At f/4, backgrounds are as soft as could be expected and we found no instances of unattractive outlining in the shots we took.
As mentioned above, while the review lens produced characteristic wide-angle distortions, they were less than we expected from such a wide-angle lens. Slight barrel distortion could be seen at 12mm but this had been corrected by 16mm and was transformed into barely visible pincushion distortion at 24mm.
The latest cameras include in-camera corrections for chromatic aberration, vignetting and distortion so these can be seen as minor inconveniences. It is also easy to correct these problems when converting raw files into editable formats with the latest conversion software from Adobe and PhaseOne.
Conclusion
For its type, the Sigma 12-24mm f/4 DG HSM Art lens is a good performer and buyers should be satisfied with the results they can obtain with it, provided they are aware of its capabilities and limitations. It’s also a lot of fun to use.
Buyers of this lens can expect sharp images at the optimal focal length and aperture settings. The lens also handles flare and backlighting remarkably well and is barely affected by distortion and vignetting for the angles of view it covers. Any shortcomings that occur are mainly with focal lengths of 20mm and 24mm, which can be overcome by swapping to a lens that covers these angles of view.
This lens is of particular interest because there aren’t many full-frame-compatible, ultra-wide-angle rectilinear (non-fisheye) zoom DSLR lenses to choose from. Canon’s EF 11-24mm f/4L USM has slightly wider coverage but otherwise similar specifications, although it costs about AU$1500 more. Nikon has a faster AF-S Nikkor 14″“24mm f/2.8G ED lens selling for around AU$2700 but it doesn’t have such a wide angle of view.
For photographers with cropped-sensor cameras, Sigma has a 10-20mm f/3.5 lens which is less than half the weight and a third of the price of the 12-24mm f/4 DG HSM Art lens and comes in popular mounts. That lens would cover an angle of view equivalent to a 15-30mm lens with Nikon DX cameras or 16-32mm on Canon’s APS-C DSLRs. The maximum aperture reduces to f/5.6 in both cases.
There’s also an even wider Sigma 8-16mm f/4.5-5.6 DC HSM lens that sells for around AU$900. Tokina has several lenses: the faster 11-16mm f/2.8 AT-X 116 PRO DX-II, which covers an 82-104 degree field of view and has a constant f/2.8 maximum aperture, the 12-24mm f/4 AT-X 124 PRO DX II lens and a compact AT-X 12-28mm f/4 lens, all of which are designed for APS-C cameras. Tamron’s SP AF10-24mm f/3.5-4.5 DI II LD Aspherical (IF) (Model AB001) is another competing lens. All four currently sell for well under AU$1000.
Nikon also has two DX lenses, the AF-S DX Zoom-Nikkor 12″“24mm f/4G IF-ED and the AF-S DX Nikkor 10″“24mm f/3.5-4.5G ED. They’re priced at around AU$1500 and AU$1100, respectively.
Although the local distributor, C.R. Kennedy and Company, has listed this lens at an RRP of AU$2399, most of the local stockists who have it listed are offering it for less than AU$2000. This is cheaper than the price listed by US re-sellers which advertise it at US$1599, which was equivalent to approximately AU$2165 when this review was posted. Add the cost of shipping and insurance and buying off-shore simply isn’t worthwhile.
SPECS
Picture angle: 122 degrees to 84.1 degrees
Minimum aperture: f/22
Lens construction: 16 elements in 11 groups (including 2 aspherical, 1 hybrid aspherical, 1 SLD and 5 FLD elements)
Lens mounts: Canon EF, Nikon, Sigma
Diaphragm Blades: 9 (circular aperture)
Focus drive: Ring-type Hypersonic (HSM)
Stabilisation: No
Minimum focus: 24 cm at 24mm focal length
Maximum magnification: 1:4.9
Filter size: n/a
Dimensions (Diameter x L): 102 x 131.5 mm
Weight: 1150 grams
Standard Accessories: Lens front and end caps, carrying pouch.
Distributor: C.R. Kennedy & Company; Aust (03) 9823 1555; www.crkennedy.com.au.
TESTS
Based on JPEG files taken with the Canon EOS 5D Mark II camera.
SAMPLES
Vignetting at f/4, 12mm focal length.
Vignetting at f/4, 16mm focal length.
Vignetting at f/4, 24mm focal length.
Rectilinear distortion at 12mm.
Rectilinear distortion at 16mm.
Rectilinear distortion at 24mm.
12mm focal length, ISO 200, 1/250 second at f/11.
14mm focal length, ISO 200, 1/250 second at f/11.
16mm focal length, ISO 200,1/320 second at f/11.
18mm focal length, ISO 200,1/500 second at f/11.
20mm focal length, ISO 200,1/640 second at f/11.
24mm focal length, ISO 200,1/320 second at f/11.
Close-up at 24mm; ISO 6400, 1/60 second at f/9.
24mm focal length, ISO 400,1/60 second at f/7.1.
Creative use of distortion at 12mm focal length; ISO 400,1/100 second at f/7.1.
Stabilisation test;12mm focal length, ISO 200, 1/4 second at f/11.
Flare at 12mm; ISO 200, 1/320 second at f/8.
Flare at 24mm;ISO 200, 1/250 second at f/8.
15mm focal length, ISO 200, 1/120 second at f/11.
12mm focal length, ISO 200, 1/10 second at f/6.3.
24mm focal length, ISO 200, 1/25 second at f/5.6.
12mm focal length, ISO 250, 1/3 second at f/9.
24mm focal length, ISO 250, 1/3 second at f/9.
12mm focal length, ISO 200, 1/125 second at f/10.
24mm focal length, ISO 200, 1/100 second at f/10.
Crop from the above image showing negligible coloured fringing.
24mm focal length, ISO 200, 1/250 second at f/6.3.
12mm focal length, ISO 200, 1/500 second at f/4.5.
12mm focal length, ISO 1600, 1/100 second at f/11.
Rating
Rating: RRP: AU$2399; US$1599
- Build: 8.9
- Handling: 8.9
- Image quality: 8.9
- Versatility: 8.5