With the retail price of the Sigma 30mm f/2.8 coming in at $199 (though currently on sale at the time of this review for $169), you’d be forgiven with not having particularly high hopes for the lens optically. However, the Sigma 30 shatters those expectations with a very, very strong showing. Right from maximum aperture, the 30mm f/2.8 produces very sharp images over the vast majority of the image frame, with only a bit of light softening at the edges. Stopping down to f/4 brings those edges and corners into very good territory, producing images with outstanding cross frame sharpness.
The level of resolution is on par with optics in the $1000 price range, rather than $200. It’s great to see that the low price is more a function of the modest maximum aperture, since Sigma did not skimp on the optics. There will be no issues with using the 30mm for images where high levels of detail are required, at any aperture. Click on the image to the right, the press the green arrow at the bottom of the screen to view a large version, which will give you an idea of the detail this lens can produce.
While not the fastest standard lens around, the f/2.8 aperture present in the Sigma 30mm is capable of blurring the background a fair bit, and for the most part, it does so in a pleasing manner. The bokeh of the Sigma 30mm is not the smoothest of any lens I’ve seen, but it also isn’t problematic. Specular highlights are mostly evenly lit and non-distracting, though some slight bright outlining can be seen in the right circumstances. If I had to describe the overall character, I’d say it’s a bit ‘chunky’. That is an odd term to use for describing bokeh, but it’s the best I can muster. Still, it lends a unique look to the images and I generally like the way things look in this department. However, those who prefer a smooth silky look will be a bit disappointed.
Contrast, Color and Chromatic Aberration
The Sigma 30mm f/2.8 DN Art features a strong contrast profile that is fairly rare among cheaper lenses. There is some bite to the images. Some of this is attributable to the high image sharpness, but the overall contrast of the images is quite high as well. This contrast actually is reminiscent of the typical Zeiss drawing style, though the Sigma differs a bit from Zeiss in how colors are rendered.
While the contrast profile reminds me of Zeiss lenses, the Sigma does render colors a bit more on the warm side, which I generally like. The color output is warm but evenly saturated. RAW files will need a bit of a saturation boost, but the color response is very good when pushed in that regard.
The Sigma 30mm controls chromatic aberration quite well. There is some lateral CA visible on the edges in the right circumstances, but nothing overly field relevant. Longitudinal CA is quite well controlled. Overall, a good showing here.
Flare, Distortion and Vignetting
The 30mm f/2.8 performs fairly well against bright light, maintaining relatively strong contrast when a bright light source is in or out of the frame. The lens also controls flare ghosting well. While it is possible to see flare artifacts in the right circumstances, it is not a common occurrence and things are well controlled here.
The Sigma 30mm has a small amount of barrel distortion that is generally unobjectionable in real world use. Lightroom has a profile for this lens to correct the distortion if you are shooting an image that has a lot of straight lines where the distortion may be noticeable. Likewise, the vignetting characteristics are noticeable, but not severe. Wide open there is a touch of corner darkening visible that is essentially gone by f/4.