The two f/11 results shown above were from the top right in some of my general results and though dark, these images show reasonable detail.

While the ribbing is all good, the position, texture and diameter of the ribbed parts increases the challenge of tactilely finding the desired ring. While there may sometimes be a slight benefit from a curved area of focus, I nearly always want a flat plane. Interesting in this case is that the corners in some of my test results (notably more-distant ones) look better when the center of the frame is used for focusing, which is much more desirable for normal use.Optics: 19 elements (including 3 special dispersion and 4 aspherical elements) in 14 groups vs. 14 elements in 13 groups for the predecessor and 20/16 for the Nikon. 14 groups have 28 air/glass surfaces that produce a lot of opportunities for flares and ghosts. We’ll see how this works out in practice. [0] The Tokina has about .5 stops less peripheral shading at f/2.8, though stopping down largely eliminates this difference.

The Nikon is significantly longer than the Sigma and is the only current comparable lens that weighs more, though only very slightly so. In the Sigma vs. Sony comparison at f/2.8, the Sony shows as the modestly sharper lens at most focal lengths With a Canon EOS 5Ds R behind this lens, I had a decent percentage of sharp handheld 24mm results at 1/5 second and still had sharp images at an OK rate at 1/4 second. The Tamron SP 24-70mm f/2.8 Di VC USD G2 is a bit worse at 24mm than the Sigma, with noticeably better results at 70mm.With a physical length of 108mm, the Sigma is a little shorter than the Canon and Tamron alternatives, and considerably shorter than the Nikon (155mm), which has an internal zoom mechanism so it doesn’t extend at longer focal lengths. The Sigma is marginally lighter than the Nikon, but a little heavier than the Canon and Tamron, weighing in at 1,020g. It’s certainly no lightweight, but nevertheless feels well-balanced even on relatively compact full-frame bodies like the Canon EOS 6D Mk II and Nikon D750. Performance A lesser 1.5 stops of corner shading is present in the 35-70mm range, again with a wide open aperture.

Taking the testing outdoors, we next look at a pair of center-of-the-frame 100% resolution crops examples. When it comes to sharpness potential, the Nikon 24-70mm f/2.8G shows remarkable performance in the center of the frame. However, this comes at the expense of mid-frame and corner performance – a typical problem for lenses with noticeable field curvature (focusing this lens at the edges of the frame will yield much better corner results, but this time at the expense of center sharpness). Sports photographers able to get close to their subjects (such as basketball shot from over or under the net) or wanting to capture a wider/environmental view of their events appreciate this focal length range. As before, the Sigma 24-70mm Art starts out weaker wide open, but once stopped down to f/4, does much better in the center of the frame. The corner performance gets much better at f/5.6 and smaller apertures. Filter-thread: 82mm just like the others except for the Tamron which uses cheaper 67mm filters. [0]

At 24mm, environmental portraits that include the venue can be captured and by 70mm, people can be framed tight enough for head and shoulder portraits while retaining pleasing perspective. In the real world, lens defects do not exist in isolation with spherical aberration and spherochromatism generally found, at least to some degree, along with axial CA. With a minimum focusing distance of 15.7" (40 cm), the Sigma 24-70 has a maximum magnification of .26x. When listing most-liked Sigma 24-70mm f/2.8 EX DG Lens features, people occasionally mention the Sigma EX finish.