Handling and Features
Performance
Verdict
Specification
Sigma has been introducing some very impressive lenses in their Art range and the latest addition is this 50-100mm f/1.8 DC lens. Designed for APS-C cameras and with a very useful constant f/1.8 maximum aperture, this gives a “35mm equivalent” of around 75-150mm. The first really high quality zooms were this range, albeit it at a more modest f/4, so it will be interesting to see how this new lens performs as it brings that specification into the modern arena.
Sigma 50-100mm f/1.8 DC HSM Art Handling and Features
For the purposes of this review, the lens was matched with a Canon EOS 600D body, a combination which offers good balance in the hand. The rotating tripod collar is placed at the centre of gravity and offers a secure attachment, plus the ability to quickly move from landscape to portrait format. Mount options are available for Nikon, Canon and Sigma and the lens is also compatible with the MC-11 adapter for Sony FE cameras, at least in its Canon and Sigma versions. If we change our mind at some point, Sigma offers a mount changing option so a change of system need not mean changing all our lenses.
Forward of the tripod collar is the zoom ring, which is nicely damped, firm in operation but smooth. Moving on towards the front of the lens we find the AF/MF switch and the distance scales. The latter are located under a reasonably sized plastic window and values are offered in both feet and metres. Focusing is down to a minimum distance of 0.95m (37.4”), which equates to a maximum magnification of 1:6.7. This is reasonable, but not as close as we have become used to with many lenses. Closer focus would have been a benefit. The lens does not rotate or extend during focusing or zooming as these functions are carried out internally.
The manual focus ring is very generously sized and has positive end stops. Action is, again, well damped and very smooth, just right for finger-tip fine adjustment of the AF, which is possible after the system has locked onto a focus point. Finally, the filter size is 82mm and a bayonet outer fitting allows the efficient petal lens hood to be quickly attached.
The lens is constructed with 21 elements in 15 groups, with 3 FLD (“F” Low Dispersion, with properties similar to fluorite), one SLD (Special Low Dispersion) and one high-refractive index, high dispersion element. The diaphragm has 9 rounded blades to ensure as round as possible an opening, for improved rendering of the out of focus areas, the bokeh. The constant f/1.8 aperture means that more control over depth of field is possible, as well as helping to ensure faster shutter speeds can be used as the light levels fall.
There are many discussions on the idea of “35mm equivalent” and although we usually refer to field of view as the comparison, it is also valid to consider the effect on depth of field. This would make the Sigma 50-100mm equivalent to the effect of an f/2.8 aperture on a 35mm format camera, offering a useful degree of differential focus. The exposure remains the same though, as f/1.8 is always f/1.8, regardless of the format. The only downside to the fast aperture is the weight of the lens, which is 1490g, which makes the original 1970s 75-150mm lenses positively svelte by comparison.
Focusing is achieved using Sigma's HSM (Hyper Sonic Motor) system, which is quiet and efficient. Manual tweaks to the AF position are possible and, of course, manual focus is also available via the AF/MF switch. I did find that it was possible to accidentally nudge the switch, so a slightly firmer one could be a good idea, or maybe relocating it to somewhere less likely to coincide with the natural grip on the lens barrel. This is, however, a minor point as in general the lens handles very well.
There are a couple of omissions, though. There is no weather resistance, a feature that would definitely be advantageous. Also, there is no vibration compensation, so no assistance with camera shake for those whose cameras rely on lens-based compensation.
Sigma 50-100mm f/1.8 DC HSM Art Performance
Sharpness reveals a very exciting performance. At 50mm the centre is outstanding from f/1.8 through to f/4, excellent from f/5.6 to f/11 and still very good at f/16. The edges are excellent from f/1.8 through to f/5.6 and are very good from f/8 to f/16.
70mm starts off centrally with an excellent performance at f/1.8, becoming outstanding from f/2.8 to f/4, excellent from f/5.6 to f/11 and remaining at a very good level at f/16. The edges are also a very high standard, very good at f/1.8 and f/2.8, excellent from f/4 through to f/8 and very good at f/11 and f/16.
85mm is centrally outstanding from f/1.8 through to f/5.6, excellent at f/8 and f/11 and very good at f/16. The edges start off at a very good degree of sharpness at f/1.8 and f/2.8, excellent from f/4 to f/11 and are still very good at f/16.
There is a similarly high performance at 100mm, with central sharpness being excellent at f/1.8, outstanding from f/4 to f/5.6, excellent at f/8 and f/11 and remaining very good at f/16. The edges are very good at f/1.8 and f/2.8, excellent from f/4 to f/11 and still very good at f/16.
MTF@50mm |
MTF@70mm |
MTF@100mm |
How to read our chartsThe blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges.The scale on the left side is an indication of actual image resolution as LW/PH and is described in detail above. The taller the column, the better the lens performance. For this review, the lens was tested on a Canon EOS 600D using Imatest. |
CA (Chromatic Aberration) results in colour fringing, and centrally the lens puts in a very fine performance. The overall values are mostly less than one tenth of a pixel, which is very creditable for any lens, never mind a zoom. The edges are not quite so well corrected, but still offer a very sound performance that can easily be corrected further in software.
CA@50mm |
CA@70mm |
CA@100mm |
How to read our chartsChromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimise the problem, hence they usually cost more. For this review, the lens was tested on a Canon EOS 600D using Imatest. |
Shooting against the light, flare was not apparent apart from a very slight reduction in contrast, and this only in the most extreme circumstances. It was basically not a problem.
Distortion affects the ability of a lens to render straight lines as straight lines, something particularly important with architectural subjects. The amount of correction is certainly very impressive. At 50mm there is -0.788% barrel, at 70mm +0.441% pincushion, at 85mm +0.964% pincushion and at 100mm +1.25% pincushion. Further correction in software is, of course, possible, but even as is the result is excellent.
Value For Money
Most lenses in the telephoto zoom bracket have much wider ranges than the Sigma 50-100mm f/1.8 DC Art lens, so its £829 price tag is hard to relate to any direct competitor. The Tokina 50-135mm T3 Cinema lens (£4499) is the closest in terms of focal length range, but hardly an easy alternative.
Of course, there are plenty of approximately 50-200mm and 55-300mm lenses available at less than half the price. With the new Sigma we lose out on the focal length, but what we do gain is exemplary performance and that bright f/1.8 constant aperture. Based on that performance, it's a fair price.
For more options have a look at the Top 10 Best Sigma lenses:
Sigma 50-100mm f/1.8 DC HSM Art Verdict
The Sigma 50-100mm f/1.8 DC Art lens is a fine example of the lens maker's art. The zoom range is limited, it's heavy and it could perhaps focus a little closer, but apart from that it would be difficult to find fault with any aspect of its performance.
The sharpness reaches outstanding levels across the range of focal lengths, distortion is low, CA well controlled and the overall appearance of the images is very appealing. The clincher is, of course, that f/1.8 aperture, which opens up a realm of possibilities in low light and for control of depth of field. A lovely lens that's a pleasure to use.
| The Sigma 50-100mm f/1.8 DC Art lens offers exemplary performance and an ultra-bright f/1.8 aperture. |