The Sigma 105mm f2.8 DG DN Macro Art is the first macro lens for Sigma’s DN-series of lenses designed specifically for mirrorless cameras with Sony E-mount and Leica L-mount. A popular focal length for macro photography and general-purpose use, it features the same f2.8 focal ratio as Sigma’s 105mm f2.8 EX DG OS HSM Macro from 2011 which was designed for DSLRs. Sigma has developed a completely new optical design for their newest macro lens and also added some nice features like a de-clickable aperture ring and an additional button which can be assigned AF-lock or other functions.
The Sigma 105mm f2.8 DG DN Macro Art is listed at 749 EUR / 799 USD / 699 GBP and should become available mid October. Ahead of my full review I’ve compared the new lens with the Sony FE 90mm f2.8 G OSS Macro and Sigma 105mm f2.8 EX DG OS HSM Macro based on the information so far available from Sigma. PS – if you’re interested in the other Sigma DG DN Art lenses check out our in-depth reviews: Sigma 35mm f1.2 DG DN Art review, Sigma 24-70mm f2.8 DG DN Art review, Sigma 85mm f1.4 DG DN Art review. There’s also lots of sample images in the Sigma 12-24mm f2.8 DG DN Art review-so-far.
Facts from the catalog
Let’s compare the Sigma 105mm f2.8 DG DN Macro Art (“Sigma Art” for short) to the Sony FE 90mm f2.8 G OSS Macro (“Sony”) and Sigma 105mm f2.8 EX DG OS HSM Macro (“Sigma HSM”). As usual I’ve rated the features with a [+] (or [++]), when it’s better than average or even state of the art, a  if it’s standard or just average, and [-] if there’s a disadvantage.
Size (diameter x length): At 74 x 134mm (2.9 x 5.3in.) plus an estimated 60mm for the lens hood the new Sigma Art is similarly sized as the Sony at 79 x 131mm (without lens hood). The Sigma HSM is 78 x 126mm w/o lens hood. These all are not small lenses. 
Weight: 719g (25 oz.) plus an estimated 35g for the lens hood. The Sony is only 602g w/o lens hood, the Sigma HSM is 725g w/o lens hood. 
Optics: The Sigma Art is a pretty complex design with 17 elements in 12 groups including one special dispersion element. This is similar to the Sony (15 elements in 11 groups) and Sigma HSM (16 elements in 11 groups). The Sigma Art has fluorine-coating on the front element to repel water, dust, and dirt and make cleaning easier – which the Sony and Sigma HSM seem to miss. [+]
The MTF chart of the new Sigma Art looks promising, certainly better than from the Sony and Sigma HSM. [+]
Closest focus distance is 0.30m (0.97ft.) with a magnification of 1:1 which is what you come to expect from a macro lens. This results in a working distance of only 0.14m. Both the Sony and Sigma HSM achieve the same magnification at similar working distances. [+]
Use with teleconverters: Yes, but only for L-mount. Sigma offers two teleconverters TC-1411 and TC-2011 which multiply focal length and maximum magnification by 1.4x resp. 2x. Whether the E-mount version of the new Sigma Art can be used with Sony’s teleconverters has to be seen. [+]
Filter-thread: 62mm, just like the Sony and Sigma HSM. [+]
Image stabilization: The Sigma Art has no optical stabilization. But the Sony A7 or Panasonic DC-S1 camera bodies provide built-in sensor-shift stabilization. Both the Sony and Sigma HSM have optical stabilization built in. 
Auto focus: Built-in AF drive with hypersonic motor. Manual-focus override is by simply turning the dedicated focus ring – same as with the Sigma HSM. With the Sony you have to push/pull the focus ring to switch between AF and MF. The focus ring of the Sigma Art probably has a variable gearing (like many lenses designed for mirrorless cameras) which allows for very precise manual focus when turned slowly but cannot be switched to linear gearing. Which makes smooth focus pulling for videographers pretty hard. The Sigma HSM has the usual linear coupling that is typical for lenses designed for DSLRs – and shows the focus distance in a small window. The Sigma Art also has an extra button on the lens which can be assigned many different functions e.g. AF-lock. All three lenses have a focus limiter: the Sigma Art offering three position as you can see below. [+]
Aperture ring: yes with 1/3 stop clicks. The lens has a switch to turn the clicks of so that the aperture can be operated continuously, smoothly, and noise-free. It also comes with a dedicated lock switch to prevent accidental shifting between aperture control from the ring or the camera. The Sony and Sigma HSM have no aperture ring. [+]
Lens profile: The lens comes with a lens profile for vignette-, CA- and distortion-compensation which can be controlled from the camera. That’s the same as with the Sony. With the Sigma HSM you have to rely on the profiles supplied e.g. in Adobe’s software. [+]
Covers full frame/FX or smaller. Same with the Sony and Sigma HSM. [+]
Price: 749 EUR (incl. 19% VAT) / 799 USD / 699 GBP. The Sigma HSM currently goes for 380 EUR / 570 USD / 340 GBP and the Sony costs 960 EUR / 1100 USD / 850 GBP. 
The lens comes with a padded pouch. The lens hood is included and probably locks in place to avoid accidentally falling off plus it is reversible for transport. [+]
Sigma’s service can change the mount of the lens between Sony’s E-mount and L-mount (at a cost). This is a unique feature that no other manufacturer offers. [++]
Sealing: yes, a rubber grommet at the lens-mount plus further special weather-sealing throughout the construction, just like the Sony. The Sigma HSM has no special weather sealing. [+]
The score in the “features-department” is 0[-]/4/13[+]. The new Sigma 105mm f2.8 DG DN Macro Art offers a nice feature set and the unique option to get the lens-mount swapped. Plus it hopefully has excellent optical performance. There’s hardly anything to complain about – on paper.
From what I can see so far the new lens should be a worthy addition to Sigma’s DN line of original mirrorless designs. Keep your eyes peeled for my full review of the optical qualities of Sigma’s 105mm f2.8 DG DN Macro Art.