Sigma’s art series has been known for excellent image quality, and I have to say, the 135mm f/1.8 Art is among the finest lenses I’ve had the opportunity to use.
I’ll cut to the chase: the Sigma 135mm f/1.8 is an absolutely blisteringly sharp lens, starting right at f/1.8. Sharpness at f/1.8 is exceptional over the entire frame, with just a touch less detail towards the edges and corners, but even here it’s still very sharp. Stopping down a bit shows only minimal improvement, but that’s because it’s hard to get much sharper than it is wide open. This may be the sharpest overall lens I’ve ever used, for any camera system. You absolutely do not need to consider sharpness at all when choosing an aperture. Pick the aperture for the depth of field you require and shoot away, knowing that the images will be pin sharp. The image below was shot at f/1.8. Click here for a 100% crop of the focus area.
Often, lenses that are extremely sharp suffer from less than perfect bokeh, but Sigma managed to avoid that pitfall here. Bokeh from the 135mm f/1.8 is smooth and creamy, with even specular highlights and a lovely character. Up close, you’ll obliterate backgrounds into nothingness, but even at moderate distances, the Sigma 135mm produces very nice background blur. Due to the extreme aperture, there is some minor mechanical vignetting that causes some elongation of the specular highlights as you get towards the edges, but I don’t generally mind that. Combined with the excellent sharpness, subjects tend to pop rather substantially with this lens.
Color, Contrast and Chromatic Aberration
The Sigma 135mm f/1.8 Art shows solid contrast straight from f/1.8 through the focus range. It’s not an in-your face high microcontrast rendering, just nice even contrast that works well for everything from portraits to landscapes. Color is perhaps a touch biased to the warm side, which is fairly typical for Sigma lenses. Surprisingly, the lens has very low chromatic aberrations, with essentially no field relevant chromatic aberration, both laterally and axially. There may be just a touch of longitudinal chromatic aberration visible in just the right circumstances, but in day-to-day shooting, I can’t say I ever really came across it. An excellent performance here.
Distortion, Flare and Vignetting
Telephoto prime lenses rarely have any issues with distortion, and the same is true here. There is a touch of pincushion distortion that is barely visible when shooting extremely straight line subjects, but unless you’re shooting graph paper, I don’t think you’d ever notice it. The lens has very minor vignetting that again won’t really be noticed in almost any situation. Even against bright light, the Sigma 135mm f/1.8 does very nicely, with just some contrast loss, but without any major ghosting.
In all, it’s a truly spectacular optic. Of all the lenses I’ve reviewed, only a handful are even close to as good optically as the Sigma 135mm. It’s simply stunning.