MINI TESTS
Panasonic cameras – as the lens is also available in Leica L-Mount – the focus can automatically stay locked on as you zoom. No such luck if you want to manually focus, though. When manually focusing for stills, the feel is pretty good despite being a fly-by-wire control design. But for filmmaking, this electronic control varies depending on how fast you turn the focus ring, so it is not repeatable like on a real manual focus lens. For this, a cine prime is for you. But then you’d be missing out on the fast, precise autofocus capabilities of the speedy Sigma’s high-response, linear actuator autofocus. It snaps into focus quickly and feels every bit as precise as the latest Sony AF lenses. One unusual feature is the 30.2cm/11.9in minimum focusing distance, which is the same at all focal lengths. Respectable for a zoom, but not as close as a dedicated prime. Image quality at pretty much all focal lengths is as good as a prime, which is very impressive. The lens is super sharp across the frame, but of course when shot wide open there is a bit of softening in the corners. Even wide open, the lens resolves loads of detail and is sharp. Colours are natural and, as with most Sigma zooms, control of flare is excellent – helped by the included lens hood. There is very little ghosting present and the contrast is high. Even when shooting directly into the sun,
In use, this quickly becomes a limiting factor. You always seem to want just that bit of extra space at the wide end or that tiny bit more at the long end. It’s not a lens for in-your- face vloggers, for example, who thrive on super-wide glass and the unique but unnatural looks this delivers. It could go wider or longer, but this would mean a smaller maximum aperture and plenty of lenses provide exactly that. Alternatively, making a 24-70mm f/1.8 lens would push the laws of physics and be significantly bigger, heavier and expensive. And, at £1299/$1349 for its 960g/2.1lb weight and large 82mm front filter size, it’s already quite a chunk to fork out for and ballast to carry around. What this can do is replace 28mm, 35mm and 45mm f/1.8 primes in a single lens, offering more precise framing for focal lengths in between. Actually, not even Sony offers these focal lengths as f/1.8 versions. The closest match from Sony is a 28mm f/2, 35mm f/1.8 and 40mm f/2.5 or 50mm f/1.8. By going with the Sigma option you’d spend roughly the same as buying three primes, but get a lens with a consistent maximum aperture and much more advanced features – from faster AF to weather sealing and, of course, the ability to zoom. Sadly, the Sigma isn’t parfocal, so the focus doesn’t stay locked on when zooming. But with the modern phase detection AF that comes in a Sony or the latest
it was difficult to provoke any nasty flare artefacts. Bokeh is excellent, thanks to the 11-bladed aperture. There are a few cat’s-eye issues at the longer focal length, but it’s not too unpleasant. In fact, the lens gives a swirly-style, vintage-look bokeh in certain shots. There is some chromatic aberration at wider settings, but it’s minimal and nothing to worry about. When we tested the lens, there was no lens correction data for our editing software, so at 45mm we experienced some pincushion distortion – and at 28mm some barrelling. There was also a small amount of vignetting in the corners. Once lens correction profiles are available and fully updated, these should easily be sorted. We tried the Sigma 24-70mm f/2.8 profiles and it worked well anyway. Build quality is excellent and the lens is resistant to the weather, with coatings to repel oil and water. Like the 24-70mm, it has every feature apart from image stabilisation. It’s a unique optic that does offer speed and quality to rival three prime lenses, but it isn’t particularly cheap or compact. If you can live with its limited zoom range, it’s a lens you will cherish. PRO MOVIEMAKER RATING: 9/10 A uniquely fast full-frame zoom Pros: Quality, three lenses in one! Cons: Limited focal length range
OPTICAL EXCELLENCE Control of flare is phenomenal (top left), bokeh smooth (above) and close focusing good, too (above left)
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