The Sigma 28-45mm F1.8 DG DN Art breaks new ground for full-frame zoom lenses as it’s the worlds first to feature a constant maximum aperture of f/1.8. That means it lets in 1.3 stops more light than an f/2.8 lens and 2.3 stops more than an f/4 lens, making it useful in low light conditions or when you want to separate a subject from its background. That constant aperture also brings the convenience of the exposure settings remaining unchanged when the focal length is adjusted.

　　Sigma 28-45mm F1.8 DG DN Art at a glance: $1349 / £1299 Large-aperture standard zoom For full-frame mirrorless cameras 30cm minimum focus 82mm filter thread 153 x 88mm, 950g Available in E and L-mount As part of Sigma’s prestigious Art series, the 28-45mm F1.8 DG DN Art is a flagship lens with high-class optics and a weather-sealed barrel. It’s available with the L Mount (compatible with Leica, Panasonic, and Sigma full-frame cameras) and the Sony FE mount. With Canon now opening up its RF mount, it’s possible Sigma may offer this lens for Canon users in the future.

　　Sigma 28-45mm F1.8 DG DN Art Features In addition to its ultra-large f/1.8 aperture, the Sigma 28-45mm F1.8 DG DN Art stands out because of its unusual focal length range. At 28-45mm, it’s significantly narrower than the commonly used 24-70mm range, a staple for many photographers. While that may seem limited, the counter argument is that its optical quality means it’s comparable to having three prime lenses in one (28mm, 35mm and 45mm).

　　The new lens is constructed from 18 elements in 15 groups, including five Special Low Dispersion (SLD) elements and three aspherical elements, which enhance image quality across the frame at every focal lengths. According to Sigma, the manufacturer has focused on precise optical corrections throughout the zoom range to minimise aberrations, aiming to deliver prime-lens quality.

　　The lens also features Sigma’s Nano Porous Coating and Super Multi-Layer Coating to reduce ghosting and flare, which is particularly beneficial when photographing backlit subjects. Also, in addition to its weather-sealing to guard against dust and moisture, the front element has a water- and oil-repellent coating, making the lens suitable for outdoor use in challenging conditions.

　　Further good news is that the zoom and focus mechanisms in 28-45mm F1.8 DG DN Art operate internally which means the lens length is fixed regardless of the focal length or focus distance. This contributes to better balance and stability, whether the lens is handheld or mounted on a tripod or gimbal.

　　Autofocusing is handled by a High-response Linear Actuator (HLA) for quick and quiet performance, ideal for both stills and video. The lens also features a bi-wire driven focus ring to deliver smooth manual focusing with a customisable rotation angle between 90 and 720 degrees on compatible cameras.

　　With a minimum focusing distance of 30cm and a maximum magnification ratio of 1:4 at 45mm, the lens is quite versatile, capable of close-up photography beyond the expectations of a typical zoom lens.

　　Other notable features include an aperture ring with a click switch and lock, and two customisable buttons. The functionality available for these buttons varies depending on the camera but generally includes features like autofocus activation and focus hold.

　　Sigma 28-45mm F1.8 DG DN Art Build and Handling Measuring 87.8mm in diameter and 153.4mm in length for the Sony E-mount version, the Sigma 28-45mm F1.8 DG DN Art is unusually large for its focal length. Its longer than both the Sigma 24-70mm F2.8 DG OS HSM (88mm x 107.6mm) and the Sony FE 24-70mm F2.8 GM II (87.8mm x 119.9mm). Weighing 950g (Sony mount) or 960g (L-mount), it is also heavier than the Sony FE 24-70mm F2.8 GM II (695g). However, this is offset by the significantly larger maximum aperture of the 28-45mm F1.8 DG DN Art.

　　In use, the lens feels similar to a 24-70mm f/2.8 lens when its mounted on a camera. Its not excessively heavy, but it’s certainly bulky for a 28-45mm lens. As with other lenses in Sigmas Art series, it has a premium look and feel. The manual focus ring at the front and the zoom ring around the centre point of the barrel move smoothly and offer the right amount of resistance.

　　The zoom ring requires less than a quarter turn to cover the full focal length range, while the manual focus rings electronic control means it has no physical endpoints. The natural support point for your left hand is the zoom ring, making focal length adjustments quick and intuitive.

　　The aperture ring, located closest to the camera body, has a pleasant, high-quality feel with optional clear clicks at every 1/3 stop. It can be de-clicked for smooth, silent operation at the flick of a switch.

　　The two customisable buttons are conveniently positioned for easy reach with your left thumb when the camera is in either portrait or landscape orientation. The AF/MF switch and the click switch for the aperture ring are both well-placed near the lens mount, while the aperture ring lock switch is on the opposite side of the barrel.

　　Sigma 28-45mm F1.8 DG DN Art Autofocus I tested the Sigma 28-45mm F1.8 DG DN Art on the Sony A7R IV and the Sony A9 III, which have excellent autofocus systems, and I found the autofocusing fast, accurate and quiet. It also proved to be compatible with Sony’ subject detection and eye detection AF. This makes the lens suitable for high-end photography and videography. In addition, focus breathing is well-controlled, with no noticeable change in framing when adjusting the focus distance.

　　Sigma 28-45mm F1.8 DG DN Art Image quality As I mentioned, I tested the Sigma 28-45mm F1.8 DG DN Art on both the 61MP Sony A7R IV and the 24MP Sony A9 III, with the Sony A7R IV being the tougher test of the lens’ detail resolution. I’m happy to say that the lens wasn’t found wanting as it delivers exceptional performance across its focal length range and at all aperture settings. At 28mm and f/1.8, the central sharpness is very good, with a slight improvement seen at f/2.0. This sharpness is consistent up to f/11, with minimal softening at f/16. The corner sharpness follows a similar pattern, maintaining quality impressively.

　　At 35mm, 40mm, and 45mm, central sharpness remains extremely good from wide open to f/2, f/2.8, and f/4. Even at f/16, diffraction softening is minimal. The corner sharpness is particularly strong between f/5.6 and f/11, with the best results at 45mm.

　　There’s only minor vignetting noticeable at the wider apertures and it’s corrected by stopping down to f/2.8 at 28mm and 35mm, and f/4 at 40mm and 45mm. In most real-world shooting situations, it’s unlikely to be an issue.

　　Curvilinear distortion is also well-controlled, with slight barrel distortion at 28mm shifting to minor pincushion distortion at 35mm and beyond. This should not pose problems for most architectural photography.

　　Similarly, chromatic aberration is minimal, with occasional minor instances in high-contrast situations being easily corrected in post-processing. The supplied petal-shaped lens hood effectively reduces flare, but it’s also well-managed without the hood or when the sun is in the frame.

　　As we’d expect, the large maximum aperture allows for significant background blur, and the lens handles out-of-focus highlights well, producing round, uniform bokeh without visible aberrations.

　　Sigma 28-45mm F1.8 DG DN Art Verdict There’s a lot to like about the Sigma 28-45mm F1.8 DG DN Art. Its optical quality is excellent, providing sharp, detailed images with minimal vignetting, distortion, and aberrations. The large F1.8 aperture is beneficial for low-light conditions and offers superior depth of field control compared to traditional zoom lenses, while also producing superb bokeh. The close focusing capability further adds to its versatility, making it suitable for a range of shooting scenarios.

　　Sigma also builds the lens to a high standard, featuring robust weather-sealed construction and practical elements such as customisable buttons, a de-clickable aperture ring, and an AF/MF switch. These features enhance its usability and appeal to photographers who demand both performance and flexibility. It’s a premium lens with a corresponding price.

　　However, some photographers may find its size and weight challenging. Those accustomed to 24-70mm F2.8 lenses will likely find it manageable, but the narrower focal length range can feel restrictive compared to their standard workhorse lenses. While the 28-45mm range has its limitations, it’s a lens that can grow on you with use. Initially, I felt it was neither wide enough nor long enough for several shooting scenarios. However, over time, I began to see it as a 35mm lens with added benefits. Despite its quirks, it left a positive impression by the end of my testing and I especially appreciated the constant F1.8 aperture.

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　　Sigma 28-45mm F1.8 DG DN Art Specifications