Sigma 24-70mm F2.8 DG DN Art Sony E Mount 578965

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At f/2.8, the Canon is noticeably sharper than the Sigma, especially in the center of the frame and in the extreme corners. Still, my lens is front-focusing slightly on my 5D Mark III at 24mm and showing some slight focus inconsistency at 70mm. So, the f/2.8 made available over the entire 24-70mm focal length range is, for the most part, best-available.

24-70mm F2.8 DG OS HSM | Art | Lenses | SIGMA Corporation 24-70mm F2.8 DG OS HSM | Art | Lenses | SIGMA Corporation

With any lens, autofocus accuracy is critically important for image quality (unless, of course, manual focus is being used) and experience has taught me that I can't always trust third party lenses in this regard. 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 greatest amount as this is where the greatest difference in the magnification of wavelengths exists. In comparison at f/2.8, the Tamron is sharper in the center of the frame and the Sigma is sharper in the periphery.As you can see, the intended plane of sharp focus remains in focus, so this issue will not be a significant one for many scenarios and focusing on a closer subject resolves the issue in many more. We tested all three lenses on the full-frame 36MP Nikon D810 to make the results directly comparable. (In our our test of the Canon-mount version, you’ll get an idea of how the Sigma Art lens fares against the Tamron and Canon models. In case you’re wondering, the Sigma isn’t a match for the Canon, which retains its position as the gold standard for this category.) Sharpness I did not have a tripod with me on this hike and wanted to use an f/8 aperture for optimal depth of field. A disadvantage of a wide aperture is the increased physical size of the lens elements that are accompanied by a larger size, heavier weight and a higher cost. An odd-number blade count means that point light sources captured with a narrow aperture and showing a star-like effect will have twice as many points as the blade count, which is 9 in this case.

24-70mm F2.8 DG DN – Sigma UK

There is also the risk of a problem that results in the lens and body manufacturers directing blame at each other. The Nikon is significantly longer than the Sigma and is the only current comparable lens that weighs more, though only very slightly so. The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple.

As I would expect for a wide aperture lens, falloff of illumination towards the corners can be quite pronounced. At 24mm and f/2.8 the corners are 2.51 stops darker than the image centre and the lens needs to be stopped down to f/5.6 to achieve visually uniform illumination. At 70mm and f/2.8 the corners are 2.2stops darker than the image centre and the lens also needs to be stopped down to f/5.6 for visual uniformity.