4) Lens Sharpness, Contrast and Color Rendition
As I reveal below, the sharpness performance of the Sigma 35mm f/1.4 is absolutely stunning – the sharpest 35mm lens I have tested so far. Center sharpness is amazing, even at the largest aperture, and I am extremely impressed by the mid and corner frame performance of the lens as well. Microcontrast is superb and color rendition is very similar to what you would get from exotic Nikkor and Zeiss lenses.
Mid-frame and corners start weaker, but still at impressive levels. Here is a sample image taken at f/1.4:
The above is almost a 100% crop from the Nikon D5200. I specifically cropped this heavy to show what you could expect from this lens.
If you want to see how the lens compares to its competitors, check out the lens comparisons section of the review, where I compare it to the Nikon 35mm f/1.4G, Zeiss Distagon T* 35mm f/1.4 and the Samyang 35mm f/1.4 lenses.
Unfortunately, the Sigma 35mm f/1.4 exhibits a similar, onion-shaped bokeh as the Sigma 50mm f/1.4 when rendering highlights. So far this has been my biggest source of complaint in Sigma lenses. It would be great if Sigma engineers found a way to make this a little less pronounced, as on Nikkor lenses. The Nikon 35mm f/1.4 also has slight definitions inside the highlights, but they are barely visible. Take a look at the bokeh comparison between the four lenses:
Although the above image shows “Rokinon 35mm f/1.4”, the image was taken with a Samyang 35mm f/1.4 branded version of the same lens. Note that Samyang sells identical lenses with different names such as Vivitar, Samyang, Rokinon, Bower, Polar, Opteka and Falcon.
On the other hand, when compared to other 35mm lenses, the Sigma 35mm f/1.4 is really the only lens that does not have the same defined “rings” that shape background highlights. Bokeh is a matter of personal preference though, so if you prefer the onion-shaped bokeh without rings to cleaner highlights with rings, then the Sigma 35mm f/1.4 would probably be your top choice. Personally, I like the cleaner bokeh of the Nikon 35mm f/1.4 and I do not mind the visible rings.
The Zeiss 35mm f/1.4 is the worst in the group, in my opinion, since it has both very defined onion-shaped bokeh and sharp rings that can make bokeh look rather distracting. The Samyang is an oddball here – it does not have the strong rings, but its highlights look rather dirty with directional wavy dots.
I have a number of sample images shot at f/1.4 that I provided in this review. I would recommend to check out those samples and decide if bokeh looks acceptable to you or not. In my opinion, unless you look at images at 100%, the onion-shaped bokeh is not very noticeable or distracting on images. Plus, if an out of focus area does not contain specular highlights, the background will generally look very smooth and creamy.
Most prime lenses heavily vignette when shot wide open, especially on a full-frame body. As expected, the Sigma 35mm f/1.4 lens vignettes quite a bit wide open, with vignetting levels falling sharply when stopped down beyond f/2. Here are the vignetting levels measured by Imatest:
When compared to other lenses, the Sigma 35mm f/1.4 vignettes more than the Nikon 35mm f/1.4 and the Samyang 35mm f/1.4, but definitely less than the Zeiss 35mm f/1.4, which is the worst in the group.
Here is the worst case scenario at f/1.4, as illustrated by Imatest:
8) Ghosting and Flare
In most cases, the Sigma 35mm f/1.4 handles flares and ghosting very well. When shot against the sun, with the sun in the corners, there is some flare and ghosting visible. When compared to other lenses, the Nikon 35mm f/1.4G clearly performs better thanks to its advanced Nano-coating technology, which produces very little ghosting and flares. The Sigma takes the second spot, while the Zeiss and the Samyang are the worst. Take a look at the below images:
Please note that the above were shot without lens hoods or filters. Using UV and other filters can potentially introduce more flares and ghosting to your images.
When it comes to distortion, the Sigma 35mm f/1.4 easily beats its competition. It has very little barrel distortion measured at 0.35%, which is almost invisible when compared to its competition. The Zeiss and the Nikon 35mm lenses seem to be at about the same level, with some visible distortion, while the Samyang 35mm f/1.4 is the worst of the group.
10) Chromatic Aberration
Lateral chromatic aberration levels are pretty light, staying under 1 pixel on average. In comparison to other 35mm f/1.4 lenses, the Sigma is the second best after the Zeiss Distagon T* 35mm f/1.4 lens. The Nikon 35mm f/1.4G shows the most pronounced amount of chromatic aberrations when compared to its competition. Here are the Imatest results:
I would not worry about lateral chromatic aberrations though, since those can be easily fixed in Lightroom and Photoshop.
As expected on fast aperture prime lenses, there is a visible amount of longitudinal chromatic aberration.