The AF motor is pretty fast and noiseless. Despite the classic design, manual focusing still works by-wire. In the case of the 65mm, this works better than on Sigma's early by-wire implementations. An image stabilizer is not provided but most qualifying cameras (E- and L-mount) offer effective IBIS these days so that's hardly a drawback.

Distortions

Enough raving about its build quality - let's go for the beef - image quality. If the Sigma 65mm f/2 DG DN Contemporary has a major weakness, it's image distortion in RAW images. A pincushion distortion of ~2.5% is certainly on the high side for a prime lens. Of course, image auto-correction comes to the rescue here so you won't notice this in real life unless you want to.

Vignetting

The Sigma is a comparatively slow lens by "50/55mm"-class prime standards, so vignetting is not a major issue. RAW images reveal a native vignetting of about 1.8 EV (f-stops) at f/2. That would be noticeable (and possibly even desirable for portraits). Stopping down to f/2.8 resolves most of this and at f/4, the issue is gone by real-world standards. Image auto-correction is primarily active at f/2 by reducing the peak.

MTF (resolution)

Please note that the MTF results are not directly comparable across the different systems!

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure of sharpness. If you want to know more about the MTF50 figures, you may check out the corresponding Imatest Explanations

Chromatic Aberrations (CAs)

Lateral CAs vary along the aperture range with a maximum pixel width of 0.75px at the image borders at f/2 - and a little less at smaller aperture settings. Once again, image auto-correction will take care of this without losing image quality.

Bokeh

Sharpness is one thing but if you are in the market for a fast prime lens, you want to use it for its shallow depth-of-field capabilities. We are pleased to report that the quality of the bokeh is just outstanding. Out-of-focus highlights are very smooth with no outlining as you can see below. This is almost surprising because the lens has two aspherical elements. Lower-quality aspherical elements tend to produce onion rings but Sigma's version doesn't fall into this category. The circular shape is mostly maintained at f/2.8 and the more edgy aperture shape creeps in at f/4 here.

The Sigma lens isn't immune to the deterioration of the highlight discs towards the borders/corners but the effect is much less pronounced than on most lenses with just a minimal tendency towards "cat eyes". Technically, stopping down helps to "fix" this. However, the results are still more pleasing at f/2 in our book.

The quality of the general blur in the focus transition zone is great in the background and still very good in the less critical foreground.

Bokeh Fringing / LoCA

Boheh fringing/LoCA is an axial color fringing effect with purplish halos in front of the focus point and greenish beyond. The Sigma lens doesn't feature an APO design (like most lenses), so there's some color fringing present at f/2. It's reduced at f/2.8 and mostly gone from f/4. This can't be easily corrected via post-processing (yet).

Sample Images

Click on an image to download the full-size variant.

Competition

There aren't really any identical competitors out there in terms of paper spec. Yes, there's the Voigtlander APO-Lanthar 65mm f/2 Macro but that's a manual lens and as such, it's not exactly mainstream. The closest competitors may be the Sony/Zeiss Sonnar FE 55mm f/1.8 (center below) and the Samyang AF 75mn f/1.8 FE (to the right). The Zeiss lens comes close in terms of being a premium product but it's optically worse. We haven't tested the Samyang lens yet but if its cousins are a guide, the build quality will be inferior and it'll also not reach the optical performance of the Sigma. However, the Sanyang lens is substantially cheaper and more lightweight.

Verdict