The DN lens has less lateral CA at the wide end, more peripheral shading at the long end, and slightly more pincushion distortion. First and foremost, there are the two other third-party 100-400mm lenses I already mentioned- the slightly older Sigma 100-400mm and Tamron 100-400mm, which were designed for DSLRs. Both lenses are optically great, you’ll be hard-pressed to detect a difference in image quality except in “laboratory condition testing”. They’re also both quite well-made, and if you take good care of them they’ll last just as long as this new Sigma mirrorless lens. Aside from the need to buy an aftermarket tripod collar, the lens handles very nicely. The balance is great when hand-holding, or on a monopod or gimbal, (the wildlife & tripod kind, not the videographer kind) …and the zoom and focus rings are nice and smooth. Personally, I still dislike lenses that have “reversed” the zoom an focus rings position, but that’s something that you can easily commit to muscle memory. Despite its small focal ratio the new Sigma has some longitudinal color aberrations (loCA, a.k.a. “axial color” or “bokeh CA”) showing mainly up at the short end as magenta coloration in the foreground. But I did not experience focus shift. Sometimes, laziness (or perhaps, "relaxation" sounds better) is a good reason to use the 100-400mm focal length range.

At the front of the lens is a non-rotating 67mm filter thread, surrounded by a bayonet mount for the Sigma LH70-04 Lens Hood supplied with the lens. The hood is made of rigid plastic and provides ample protection to the front lens element.

Then again, many wildlife photographers (who want to go longer than 200mm) find themselves shooting at sunrise or sunset, and f/5-6.3 are pretty dark apertures to try and photograph any moving subject, even from a tripod. You could go with the alternative, that is a Sigma 70-200mm f/2.8 Sports, (a virtually flawless lens) …and enjoy the benefits of f/2.8 in extremely low light, while adding a 2X teleconverter that could allow you to get to 400mm and “only” be at f/5.6, instead of the Sigma 100-400mm’s f/6.3 (at 400mm).

In comparison to the Nikon the new Sigma produces a softer FF/FX-corner but otherwise looks very similar.

Price, Value, Wrap Up

The following is a review of the Sigma 100-400mm F/5-6.3 DG OS HSM Contemporary lens which was released in February of 2017 as part of Sigma’s affordable “Contemporary” lens lineup. The introduction of the Sigma 100-400mm F/5-6.3 DG OS HSM C lens is a logical one for the company as it competes in a market segment that remains unexploited by the likes of Canon and Nikon. In regards to specs and measurements, the Sigma 100-400mm f/5-6.3 DG DN OS Contemporary Lens vs. Sigma 100-400mm f/5-6.3 DG OS HSM C Lens comparison shows the DN lens slightly longer and extending slightly longer still. Sigma’s new lens performs best around 155mm focal length where it is very sharp across the full frame. On the short end the FF/FX-corner suffers a bit and towards the longer end the lens becomes gradually softer with 400mm being the weakest length of the lens. Still the performance at the long end is very respectable. If you want to see all the details and comparisons with the competition from Nikon, read on. Or fast-forward to the performance at long distances. These charts show the lens-performance of both lenses at their largest aperture without influence of diffraction. This is a bit misleading as diffraction at apertures of e.g. f6.3 already robs 10-15% of contrast from the reproduction of finest details. The Nikon 80-400/4.5-5.6G VR is also at a slight disadvantage as its focal ratio is 1/3 of a stop brighter. To read these charts you need to know that higher values are better and the closer the line-pairs are together the less astigmatism (= resolution depends on the orientation of the test-pattern) the lens has. The x-axis displays the distance from the optical axis (=center of the sensor) in mm. I’ll show you the real-life performance at 4 mm (center), 13 mm (APS-C/DX-corner), and 20 mm (FF/FX-corner) on a 36MP Nikon D810 body. The second group of lenses is made up of other 80/100-400mm zoom lens offerings, of which only the Sigma 100-400mm f/5-6.3 HSM DG OS C is in the same price range as the Tamron lens. Indeed, the Sigma 100-400mm C is the Tamron’s closest competitor, and the two lenses offer a very similar feature set overall. The Tamron benefits from having a fully weather-sealed construction and better focusing performance. When it comes to which lens is sharper, both models have some distinct advantages, though the overall impression is quite similar. Generally, the Tamron is a bit sharper centrally from 100mm to 300mm, while the Sigma generally offers better corner sharpness. At 400mm, the two lenses are incredibly similar, with the Tamron a hair sharper in the center of the frame at f/6.3, and the Sigma a hair sharper at f/8. The Sigma also maintains a slight advantage in the image corners at the 400mm setting. NIKON D780 + VR 100-400mm f/4.5-6.3E @ 400mm, ISO 400, 1/500, f/6.3

In this case, the just-over 1 stop of shading showing at f/ may be visible in some images, especially those with a solid color (such as a blue sky) showing in the corners.

The Sigma 100-400mm F/5-6.3 DG OS HSM C is a well-made lens, with an optical design of 21 elements in 15 groups. Four of those are SLD (Special Low Dispersion) elements to help increase contrast and sharpness while minimizing color fringing. The lens relies on Sigma’s ring-type HSM (Hyper Sonic Motor), which has been a mainstay on the company’s lenses for many years. You’ll also find an autofocus range limiter to help speed up focus acquisition, as well as Optical Image Stabilization with roughly four stops of compensation (Sigma doesn’t specify, but that’s what I found in my tests). Therefore, at the end of the day, this newest mirrorless Sigma 100-400mm is probably your best overall value, and if you don’t already own one of the previous 100-400mm’s, then you should just get this one! Sigma 100-400mm DN Review | Cons Built to do full justice to Sony’s prestigious Alpha A7 and A9 series full-frame mirrorless cameras, this lens also works a treat with APS-C format E-mount bodies, where it gives an effective zoom range of 150-600mm. Build quality is fabulous, with a really solid yet refined feel to the construction and a more comprehensive set of weather-seals than is fitted to Sony’s 70-100mm G-line lens for it’s A-mount cameras. In the meantime, I was able to review this new milestone of a lens on both the Sony A7R IV and the Sony A9 II, plus, using the TechArt adapter I was able to mount it on the Nikon Z7 and the brand-new Nikon Z5!

A full set of switches is on hand for AF/MF focusing, an autofocus range limiter and dual-mode optical stabilization for static and panning shots. Buttons around the forward end of the lens enable a autofocus-hold function. The zoom ring has variable friction damping, applied via a separate ‘zoom torque adjustment ring’. While a full-frame camera-mounted 400mm lens may still seem short when photographing deep into large-field events, in front of an APS-C model where it provides an angle of view equivalent to a 150-600mm lens on a full-frame camera, Because aperture is measured as a ratio of lens opening to focal length and because this lens' maximum opening does not increase adequately with focal length increase to maintain the same ratio,Lateral CA shows as color fringing along lines of strong contrast running tangential (meridional, right angles to radii) with the mid and especially the periphery of the image circle showing the most significant amount as this is where the most significant difference in the magnification of wavelengths typically exists. Below you can see some of the more spectacular effects at 100mm focal length with the light inside the image circle near the center (see left image below) and some surprising glare where the light is well outside the image circle but still shining into the lens (right image below).