Sigma 50-100mm f/1.8 DC HSM Art: Mastering the Art
The Sigma 50-100mm f/1.8 DC HSM Art is the fastest constant aperture zoom of its kind, providing undeniable advantages. Shridhar Kunte reports.
With APS-C sensors reaching new heights in terms of resolution and performance, Sigma was the first company to respond with the seminal 18 – 35mm f/1.8 DC HSM (tested in the Jan 2014 issue of Better Photography). Following in its footsteps, the second lens in its line-up is the new 50 – 100 f/1.8 DC HSM. The lenses enable two extremely important advantages for APS-C users. Firstly, it delivers the same level of bokeh and control over DOF as f/2.8 lenses on a full frame sensor. Secondly, given the same resolution, the extra 1.3 stops of aperture allows APS-C sensors to have the same level of noise performance as full frames with f/2.8 lenses. So far, none of the other manufacturers have addressed this gap.
The 50 – 100mm has an equivalent focal length of about 75mm to 160mm. The minimum focusing distance for this lens is 0.95m, at which the magnification ratio is 6.7 times less than life size. With a zoom ratio of just 2x, the lens construction is very complex, with 7 special elements out of 21, arranged 15 groups. These elements have a special coating to improve light transmission, colour consistency and to reduce flare. Both zooming and focusing is internal, ensuring that the overall length remains the same and that the front of the lens does not rotate (a big plus for CPL and ring flash users). The Hyper Sonic Motor allows faster noiseless focusing, with full-time manual focus override. The lens accepts 82mm filters. This, unfortunately, is a big issue especially in India. 82mm filters are not only difficult to find, but are also expensive.
We received the Nikon version of the lens. Out of the box, it feels very well built and beautifully finished, in line with Sigma’s now famous Art series. I used the lens with the Nikon D7200 for most of the time. It is a large, metal-bodied lens with a metal mount, and will feel more at home in larger hands. In terms of both weight (1490 grams) and balance, it is not dissimilar to the new full frame Nikkor 70 – 200mm f/2.8E VR (60 grams lighter). It harmonizes reasonably well with larger APS-C DSLR bodies.
The MF ring in front of the zoom ring offers good damping and rotates by about 95 degrees across the focus range. Both rings are ribbed, comfortably separated, and afford a good grip. The lens comes with a tripod collar that sits quite close to the zoom ring, and it is not removable. It can be rotated and locked quickly into one of four marked positions though, so that it does not get in the way of operating the zoom. There is no stabilization, which is a tradeoff for its price and large optics.
While the bokeh at f/1.8 on the APS-C sensor is quite fantastic and equivalent to a full-frame at f/2.8, the best optical performance from this lens is when used at f/2.8 to f/4. The center sharpness is excellent at f/1.8 at all the focal length. There is visible light fall-off wide open, but this evens out from f/4. While shooting against the sun, control over flare is rather good with a minimal loss of contrast. High contrast scenes display some purple fringing at the wider focal lengths, and disappears towards the telephoto end. There is hardly any distortion. Focusing speed and accuracy is excellent. Despite the f/1.8 aperture, I personally missed IS in low light.
With the new 50 – 100mm f/1.8 DC HSM Art, Sigma has produced a lens that offers undeniable advantages for APS-C DSLR users who shoot wide open. It is not small in size or light to carry. Yet, the constant f/1.8 and optical performance places the lens in the category of a prime, or rather, several f/1.8 primes packed into one, making its price of Rs 95,900/- well worth it despite the modest 2x zoom. Those who do not need these particular qualities, however, would be better served by the flexibility of a full frame 70 – 200mm/f2.8 lens with IS, which would cost much more but offers an upgrade path to a full-frame camera.
HSM AF motor, f/1.8
Excellent Sharpness, light fall off
No weather sealing, Metal construction
Full time manual focus override, Small tripod collar
|Warranty & Support
Two-year warranty, limited service in India
|VALUE FOR MONEY||3/5|
|Who should buy it?||Street and Specialized portrait
photographers who shoot a lot in low lighting conditions.
|Why?||It offers convenience and performance of multiple