(Credit: Sigma)
Photographers capturing night sky images often reach for wide angle lenses to create compositions that incorporate both landscape and stars, and chase extra-bright optics to keep exposure times reasonable and improve manual focus accuracy. Sigma's latest lens, the 15mm F1.4 DG DN Diagonal Fisheye Art, fits those requirements to a tee. It's a full-frame lens, available for Sony E and L-Mount Alliance systems.
The 15mm F1.4 Fisheye sports a frame-filling 180-degree diagonal angle of view, so it sees everything in front of it. It manages this feat by drawing a scene with serious curved distortion, the effect that gives a fisheye lens its name, for a broader view than rectilinear lenses that make an effort to keep straight lines straight in photos—the Sigma 14mm F1.4 DG DN Art, another favored option for night sky work, is narrower at 114.2 degrees, as an example. Fisheye lenses are uncommon in the mirrorless era, and this is the first we've seen with autofocus for both Sony and L-Mount systems.
Astrophotography Features
The angle of view makes for dramatic scenes, though it puts more onus on the location and camera location versus lenses that see a narrower view. And while astrophotography is an obvious use case, there are other disciplines where the lens makes sense. Fisheyes are popular for tight interiors and sports where you can get up close with the athletes like BMX biking and skateboarding.
(Credit: Sigma)Astrophotography is an outdoor discipline, so we consider it a good thing the Art series lens is dust- and splash-protected, and has anti-smudge fluorine on its bulbous front element. Like the others in the Sigma astro family—the aforementioned 14mm F1.4, the 20mm F1.4 Art, and 24mm F1.4 Art—the barrel includes an extra-wide space behind the front element to accommodate a heat retainer. The clearest nights are often the coldest nights, and condensation can ruin a long exposure, so it's wise to add a warmer (not included) to counter fogging.
The lens also includes a manual focus lock switch, so there's no chance of ruining your shot by accidentally nudging the focus ring. Autofocus is supported too. The 15mm Fisheye uses a linear HLA motor and promises a snappy response, so you can use it for subjects in motion too, not just star fields and landscapes.
The 15mm F1.4 is sizable; its chunky barrel comes in at 6.2 by 4.1 inches (HD) and it's heavy for the size at 3.0 pounds. Its optical formula is complex, it uses 21 glass elements arranged in 15 groups, accounting for its weight. The lens makes compatible cameras front heavy enough to call for a tripod collar and foot. The collar is integral to the design and includes dovetail cuts so the lens can go directly into an Arca-Swiss tripod head with no additional release plate needed.
(Credit: Sigma)We've not had a chance to test the lens, but Sigma promises that its optics are not just sharp, but they also work to suppress flare and maintain contrast against a strong backlight, pluses for use in daylight. Close focus is achievable too, the lens locks on to subjects as near as 15.2 inches from the camera. Magnification is meager (1:16), but focusing close puts a subject against an expansive background, something you can use for dramatic juxtaposition in photos.
Pricing and Availability
The 15mm F1.4 DG DN Diagonal Fisheye Art is set to ship on March 7 for $1,999.99 in your choice of E-mount or L-mount. We haven't had a chance to try the lens yet, but hope to review it soon.
We've already reviewed Sigma's other announcement today, the 500mm F5.6 DG DN OS Sports, a lightweight telephoto for the same systems that's well-suited for wildlife and field sports. It's shipping a week later, on March 14, and pricier at $2,999.99.