I have to admit, I have a soft spot for the 24-70mm zoom lens. A little weird having emotional attachment to a focal length range, but this lens was my first, top quality zoom lens back in the day. In my case, it was the Canon L-series version which covered the most usable focal lengths and served me extremely well from landscapes to wedding photography. In this regard, we are looking more closely at the Sigma 24-70mm f/2.8 DG DN Art lens.
The Sigma is one of three lenses available for the full-frame mirrorless Sony E and Leica L mounts. This makes it a different proposition from the DSLR version from 2017, available for Canon and Nikon mounts and also featured image stabilization. As the new lens is built specifically for the mirrorless format, it uses focus by wire and a dedicated button which can be set for various camera parameters. A Canon and Nikon version is hopefully in the works, but for now we will check out how this lens operates on a Sony a7R II body.
First impressions of the lens are that it follows the ‘Art’ series with its simplistic layout. It’s also reasonably compact at 88 x 125mm, with an extending lens barrel when zoomed in. The lens is also verging on the light-heavyweight class at 827g. Not overtly heavy, but still needing an ample hand hold on a mirrorless body.
The optics of the lens are arranged with 19 elements in 15 groups, including eight dispersion (Six F Low Dispersion (FLD) and two Special Low Dispersion (SLD)) and three aspherical elements. A Super Multi-Layer and Nano Porous Coatings have been applied to reduce aberration, such as reflections, flaring, and ghosting.
Close focusing distance is reasonably good at 18cm, with a maximum magnification of 0.34x. There’s also an 11-blade rounded diaphragm, which should in theory produce more rounded bokeh balls than a nine-blade version.
There is no image stabilization on this lens, which means it’s wholly down to the camera body for anti-shake duties. A stepping AF motor has been used for autofocusing, which has a manual focus override. The focus ring itself is extremely smooth in its workings, with a large turning circle for very precise manual focusing. There’s also no DOF markings on the lens barrel, which is usual for mirrorless lenses.
The lens barrel has two switches and a focus lock button. The two switches include one for AF/MF and a zoom lock switch keeping the lens barrel in place at 24mm. Unlocking the zoom can also be done by turning the zoom ring. The focus lock button can also be assigned to various camera settings, such as focus lock. Also of note, the lens isn’t fully weather-sealed, but it does have a rubber grommet around the lens mount to keep out dust and moisture.
Lastly, the Sigma 24-70mm f/2.8 DG DN Art lens has a 82mm filter thread, fitting the included petal shaped lens hood very tightly.
The Sigma 24-70mm f/2.8 DG DN Art In Use
With a reasonable amounts of light, the Sigma is fast to lock onto focus throughout the focal range. The only missed shots occurred when the lens was in near darkness or too close to a subject to focus.
The zoom ring located at the back of the lens turns very smoothly and the zoom lock can come in very handy to stop zoom creep at 24mm. The wider focus ring, located at the top of the lens barrel, can be sensitive to the touch, so you always have to be mindful that it doesn’t accidentally go into manual override with the slightest movement.
When it comes to chromatic aberration, even when wide open, there is no evidence of fringing. Even on high-contrast areas, which is a great benefit to this lens. Fringing can be removed to an extent in post-processing, but when it heaped on in heavy amounts, as with some lenses, it can sometimes make or break a shot. Luckily, you will not have that headache here.
Center sharpness on the Sigma is impressive up to 35mm with the aperture wide open, with slight softening in the corners as you approach 70mm. Detail across the frame tidies up very well by f/4, with the overall best results coming in at f/8. Diffraction starts to take a toll after f/11, but in general, images have the clarity and detail on par with the DSLR equivalents.
Light falloff can be seen at f/2.8 in the corners, more so at 24mm, starting to clean up nicely by f/5.6 and virtually eliminated by f/8. Vignetting is less apparent at 70mm and by f/5.6 is virtually non-existent. The lens also isn’t devoid of distortion, being most prominent at 24mm, with a slight pin cushioning effect at 70mm.
The 11-blade diaphragm, while producing hard edges of light, produces nicely rounded bokeh balls. There is evidence of mild onion rings, but the extra rounded off details are most pleasing. General background blur is respectable, with good transition of colors, but not to the qualities you would find on a high-end prime lens. Still, very respectable.
For general shooting scenarios, ghosting and flaring are kept in check, but if you catch direct sunlight or a strong point of light, artefacts can occur. This is the most evident at 70mm producing light flares, but at close ranges, points of light can produce nice looking sun stars if the light source is quite near. Far off light sources tend to be rendered as more blobs of light.
How Does It Compare?
The Sony FE 24-70mm f/2.8 GM would be an obvious comparison, but it costs more than twice the amount of the Sigma 24-70mm f/2.8 DG DN Art lens. Just in monetary terms alone you would expect the Sony version to be in a different league, so it’s more viable to compare the Sigma to the Tamron 28-75mm f/2.8 Di III.
The Tamron is very sharp in the center of the frame across the focal lengths, but does exhibit corner softness. The Sigma is much better in this regard. In comparison, the Sigma has better bokeh rendition, plus the extra 4mm at the wide-angle range. The Tamron is also the cheaper of the two lenses.
|Sigma 24-70mm f/2.8 DG DN Art||Tamron 28-75mm f/2.8 Di III|
|Optics||19 elements/15 groups||15 elements/12 groups|
The Sigma 24-70mm f/2.8 DG DN Art has a lot to prove with this type of zoom. The f/2.8 aperture works very well in low light and can easily produce very good bokeh renditions. Sharpness levels are good across frame, with the most obvious softening in the corners at close. It’s fast to focus, shows very little sign of chromatic aberration, and light falloff at the edges are perfectly manageable.
Images become noticeably softer at close focusing distances, but more than a meter away from a subject, images are at least as detailed and full of contrast, compared to the competitors. When you consider the price point, the Sigma 24-70mm f/2.8 DG DN Art is a viable alternative to same brand lenses and even has the advantage of a mount swap from Sony E to Leica L-mounts at a cost.
Overall, and considering the price point, the Sigma is a viable alternative to regular 24-70mm offerings, with the only letdown being the softness of images at very close distances. If you need a 24-70mm lens that features high-end optics without breaking the bank, the Sigma is a definite lens to shortlist.