Sigma 15mm f/1.4 DG DN Art Review: Wide, Weird, and Wonderful

It’s not often that I get to review a lens that the world has never seen before. I’ve reviewed plenty of f/1.4 lenses and I’ve reviewed the occasional 15mm fisheye, but a 15mm diagonal fisheye with an f/1.4 maximum aperture is a first for me.

Although fisheye lenses are a very specialized tool with limited applications, it’s always refreshing to head out for the day with a challenging limitation to work around.

At first glance, you’d be forgiven for thinking this is the Sigma 14mm f/1.4, which is a lens that I personally love for astrophotography and low-light landscapes. Both it and this new 15mm f/1.4 have a very similar body design and are brilliant in darker scenes, but that is where the similarities end.

Finding a fun application to test the Sigma 15mm fisheye proved challenging. Still, a visit to the National Music Centre provided an ideal environment for low-light tests as well as interesting architecture to shoot within.

Sigma 15mm f/1.4 DG DN Diagonal Fisheye: How It’s Built

Being an Art series lens, the Sigma 15mm f/1.4 DG DN is sturdy and well-sealed. There is a sophisticated lens cap designed to protect the integrated lens hood and bulbous front element as well as a customizable function button. There is also a proper aperture ring with the option for smooth or click-stop functionality as desired.

The manual focus ring is well dampened and there is a manual focus locking switch that disengages focusing altogether, even if the ring is accidentally turned. This control is handy for astrophotography situations, something that the Sigma 15mm f/1.4 is designed for. This is a handy feature that prevents any manual focusing even if the ring is accidentally bumped or turned. You can also turn off your camera and turn it on again and the manual focus point will be retained.

Being a fairly heavy lens at 48 ounces (1,360 grams), the 15mm f/1.4 does have a removable lens collar to better distribute the weight on a tripod. The foot of the collar is cut to accommodate Arca-style tripod mounts, which I always like to see.

Sigma 15mm f/1.4 DG DN Diagonal Fisheye: How it Shoots

The indoor location we shot in provided plenty of opportunity for lens testing. However, our initial testing started outside and one of the first things I wanted to check was flare resistance. Sigma has excellent coatings overall and the Sigma 15mm had no issues with loss of contrast or ghosting. This is especially useful given how wide the lens is and how much glass there is at the front. You can happily shoot this lens toward bright sources of light without issue.

Sunstars are also interesting out of this lens. We don’t get the sharpest, most well-defined points, but the 22 points are dramatic looking thanks to the 11-bladed aperture inside. LoCa, or longitudinal chromatic aberration, is something I specifically look for on wide-aperture lenses but luckily I didn’t see any here. These color casts in areas of soft focus can be difficult to remove in post but thankfully that wasn’t an issue on the 15mm f/1.4 fisheye.

Bokeh is clean for the most part with a strong cat’s eye vignette at f/1.4, which I think looks quite nice. Stopping down the lens eliminates it though, and specular highlights become round and smooth looking. This lens has beautiful bokeh with a lovely transition as the image goes out of focus.

Sharpness was especially impressive at f/1.4 when focused near infinity as the frame is evenly in focus from the center to the corners. This is very useful when shooting expansive skies full of stars where the pinpoints of light remain clear throughout the frame. Stopping down the lens is only marginally useful as far as sharpness goes, however, there is one major caveat.

The Sigma 15mm is sharp at a distance but when the subject is within a few feet the image can get very blurry in the centers at f/1.4. Stopping down the lens helps immensely with any closer subjects but I wouldn’t shoot at f/1.4 unless my subject was well beyond arm’s reach.

Despite the fun we had shooting the 15mm, it was actually designed and intended as a tool for astrophotographers looking for something unique to play with. Unfortunately, Calgary has been subject to freezing temps and snow storms and we have had nothing but cloud cover and hazy conditions.

Even sharp cityscapes were impossible to get for the time we had the lens. Luckily, Sigma provided some full-resolution images that we could evaluate and it looks like this lens is a winner.

Issues like soft corners and excessive coma have been corrected exceptionally well, even when shooting at f/1.4. There appears to be no sagittal astigmatism either, which causes corner stars to look like batwings or butterflies. Therefore, the Sigma 15mm f/1.4 is the ideal tool for someone who wants an astrophotography lens with the funkiness and curved horizons that a diagonal fisheye creates.

The Sigma 15mm f/1.4 DG DN Diagonal Fisheye is an Engineering Marvel

As good as this lens is, it will still be a very niche product for a select few photographers. However, the engineering required to even make such a lens is no small feat and the 15mm f/1.4 is certainly a feather in Sigma’s cap.

I could see the 15mm being popular as a rental lens for the occasional production or as a mainstay for a music video or concert photography creator. Landscape photographers and astrophotographers should absolutely consider this lens as well to create something a little different.

Are There Alternatives?

There is nothing like this lens on the market. As diagonal fisheye lenses with an f/1.4 aperture go, this is really it. Slower fisheye lenses can be found or adapted, but for low-light or astro work, this is the lens to choose.

Should You Buy It?

Maybe. The lens performs very well but its unique look makes it niche. Determining if you need it or not comes down to whether you specifically want a diagonal fisheye look in low-light situations.