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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. In comparison at f/2.8, the Tamron is sharper in the center of the frame and the Sigma is sharper in the periphery.
24-70mm F2.8 DG OS HSM – Sigma UK
Since Sigma reverse engineers (vs. licenses) manufacturer electronics and algorithms, there is always the potential for a DSLR body to not be supported by a (likely older) third party lens. The Sigma 24-70mm f/2.8 DG OS HSM Art Lens is available in Canon (reviewed), Nikon and Sigma mounts and the Canon mount version can be used on a Sony E-mount camera body via the A 24-70mm lens is expected to have distortion – barrel at the wide end that transitions to pincushion at the long end. Taking the testing outdoors, we next look at a pair of center-of-the-frame 100% resolution crops examples. 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.
That being said, the minimum focus distance of just 7.08 inches (18 centimeters) is quite nice, and it allows you to get quite close to your subjects for some gorgeous bokeh and fall off when shooting wide open. Usually a lens can be made compatible by the manufacturer via a firmware update, but this cannot be guaranteed. Zooming in to the 70mm position the story is pretty similar, with a great level of detail in the center but rather softer corners when shooting wide-open. Again, stopping down to F5.6 helps throughout the image. That said, the improvement in the center is less dramatic at telephoto and the improvement in the corners is more noticeable than it was at wide-angle.
24-70mm 2.8 VR vs Sigma Art vs Tamron G2 - Fstoppers Nikon 24-70mm 2.8 VR vs Sigma Art vs Tamron G2 - Fstoppers
Spherical aberration along with spherochromatism, or a change in the amount of spherical aberration with respect to color (looks quite similar to axial chromatic aberration, but is hazier) are other common lens aberrations to look for. At 24mm, corners are darkened by about 3 stops at f/2.8 while the 28mm and 70mm focal lengths see about 2.5 stops of wide open corner shading. Magnification from wide angle through standard/normal focal length lenses, including this one, is generally significantly increased with the use of extension tubes which are basically as their name implies, hollow tubes (with electronic connections) that shift a lens farther from the camera. The Sigma 24-70mm f/2.8 DG OS HSM Art Lens features a dust/splash-proof construction including a rubber gasket seal at the lens mount. We achieved the best results at mid-range, at 35 and 50mm, but it is a good performer at the wider end as well, albeit with some astigmatism. Like others in this group, there’s a noticeable drop in sharpness at 70mm.
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At f/4, I like the Sigma results slightly better at the long end and the Nikon appears to be slightly sharper at the wide end, though the CA definitely gets in the way of the latter comparison. Differences even out considerably at f/4, where the Sigma generally has slightly sharper center of the frame performance and the Tamron takes a couple of corners. This lens becomes extremely sharp when stopped down one stop and any differences realized by stopping down to f/5.6 are minor in this portion of the image circle. While the Sigma lens is physically shorter and lighter than the Sony 24-70 f/2.8 GM (5.35″ long, 1.95lbs), it is still substantially larger than the Tamron 28-75; the Sigma weighs 1.84 pounds compared the the Tamron’s 1.21, about 65% as much as the Sigma. Matthew Gore | Light And Matter Selecting the lowest distortion focal length (around 28-30mm) takes care of the distortion problem (and removal during post processing is always an option at other focal lengths).
Sigma 24-70mm f/2.8 EX DG HSM Interchangeable Lens Review Sigma 24-70mm f/2.8 EX DG HSM Interchangeable Lens Review
A shoulder strap is not provided/available for this model, but an approximately 1.75" (44mm) belt loop is.Overall, the lens is well-built with essentially no play/wobble in the barrel assembly even at full extension. The graph below shows the degree of corner shading visible in images from the three lenses at their longest focal length and widest aperture (when it will be most noticeable). Most modern lenses have lens correction profiles available for the popular image processing software (though most cameras will not have this correction available for a Sigma lens) and distortion can be easily removed using these, but distortion correction is destructive at the pixel level and
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