What's better than being excellent? Being good. The pro-level Nikon D3x was excellent. Years later, the entry-level Nikon D3300 is merely good, but even at the same resolution, it arguably delivers cleaner and crisper image files under ideal conditions. Yes, of course, you can't compare apples to oranges, and no matter how good a consumer camera, it doesn't do the job of a professional one. At least in image quality, the Canon EOS T5i has the benefit of time and the march of technology over the 1D Mark II. That's not a fair, accurate nor appropriate comparison, but there is a little bit of truth to it.
So let's try this again. The Zeiss Otus is excellent. The Sigma 50mm f/1.4 DG HSM Art is good. And yes, this time, you actually can mention both in the same breath.
Build and Design
What do you give up when you go from the Otus to the Art lens? Full-time manual focusing for one. The 50mm f/1.4 Art in your hands feels exactly like it looks, like the bigger brother to the 35mm f/1.4 Art. It's a long and weighty lens, betraying how much glass Sigma put into it to produce the optical quality that it does. "Big" is relative, though. It's big for a prime, but in terms of length and weight, it's like mounting the Canon 24-70mm f/2.8 on the 5DmIII. That's still a heavy combination, but the point is that the Sigma is still do-able if you want to use it as a "walk-around" lens.... which is not the point of this lens, since many people insist on having that as a priority, then yes, it is capable of doing that.
If you aren't familiar with the new Global Vision Sigma lenses, the casing is made from a composite material that has an appearance midway between being metallic and glass-like. The overall impression of the flat gloss finish is upscale and arguably more attractive than what either Canon or Nikon package their lenses in. While we are at it, a case could be made that the 50mm Art is more attractive looking than the Otus. The Zeiss lens has a distinctive look, but it also looks like an overgrown Touit lens.
Like it's 35mm little brother, the focus ring is a wide flat band that is easy to grab a hold of, and has a large degree of fluid damping for precision manual focusing. Focus is quick and quite in much the same way that Nikon's AF-S or Canon's USM lenses work. The front filter size is 77mm, which is not uncommon nowdays for DSLR equipment, but which is exceedingly large for a 50mm prime. There will be two schools of thought about filters and this lens. The first would be that since you would be using this lens to grab the utmost in terms of sharpness and resolution, a protective filter would be antithetical to its purpose. The second school of thought goes along the line of: "It's a $1000 lens..." That depends on comfort level; for some people that is dear amount of money, for others it isn't. However, be warned that to match the optical level of this lens, you would need the highest quality, something on the order of a B+W 77mm XS-Pro UV MRC-Nano or the Hoya 72 mm Pro1 Digital MC UV-0. Filters at this size and of this quality don't come cheap.
Here's what the 50mm Art looks like when mounted on the Canon. The longish profile and slimming-black cosmetics wide the fact that it's bigger and heavier than even the Canon 50mm f/1.2 L.In term, the Zeiss 55mm f/1.4 Otus is bigger and heavier still.
Bokeh and Contrast
(Click here to see an extended sample set of the Sigma compared to the Canon 50mm f/1.2L)
The following were taken with the Sigma 50mm Art mounted on a Canon 5DmIII, out of camera JPEG. (Though the test framing is not identical, it is also interesting to see how this lens compares to the Nikon 58mm.) Though you can make out some vignetting with the lens wide open, it's quite low for a fast prime, and what's more, the transition in brightness from corner to center is gradual, lessening the visual impact of the falloff. Even without commenting on the sharpness and contrast, this is already an excellent lens from the standpoint of geometric distortion and chromatic aberration control. (Vignetting and geometric distortion aren't corrected for by the first-party cameras when third-party lenses are used.) In one important aspect, the 50mm meets the definition of what professional glass should be: unobtrusive. The optical qualities are unobtrusive, there isn't much that you have to shoot around or try to avoid.
For instance, on older designs like the Nikon 50mm f/1.4G or the more expensive Canon 50mm 1.2L, you tend to avoid shooting wide-open unless you are going for a specific look. That's even true for of the Nikon 58mm f/1.4 "Noct," which doesn't necessarily give a convincing display at f/1.4 in daylight conditions. That's not true of the Sigma, though, which is extremely contrast right at f/1.4. Corner contrast naturally lags a bit, but is still better than the Canon/Nikon alternatives. By f/2.8, the lens has pretty much entered a big, fat sweet spot of sharpness.
|Sigma 50mm f/1.4 DG HSM Art on Canon 5DmIII, at f/2.8|
|Sigma 50mm f/1.4 DG HSM Art on Canon 5DmIII, at f/4|
Often, the tradeoff with pushing sharpness within the focal plane is that the out-of-focus background rendition ("bokeh") may suffer. You can see this comparing the Sigma 35mm f/1.4 versus its Nikon rival; the Sigma is tuned for more center contrast, but the Nikon has the smoother background bokeh.
The 50mm Art is not bad in terms of bokeh quality, but here is where the Nikon 58mm really shines. The canon 50mm f/1.2L is also smoother and creamier. The quality of the 50mm Art's bokeh is "good" but a little on the harsh side; not quite falling into the "nervous" category but it definitely could not be counted as one of the "creamiest" of lenses. Mind you, the background setup was deliberately picked in these test shots because of how busy the scene is, so this is really a worst case-scenario. The immediate background just behind the terracotta warrior figurine, which is simpler, comes out smooth at all apertures. Note that at f/1.4, even though the center contrast is slightly reduced, the details on the figurine are rendered quite crisply; by f/2 the center contrast is strong enough that there is virtually no additional benefit to stopping down.
How did Sigma achieve these results at this price point? The larger answer is that company made investments in their design process that are paying off across the board, not just with this lens, but with virtually all of their new Global Vision lenses. The more specific answer is that the 50mm f/1.4 Art visually looks as a sharp as the Zeiss Otus, but it does so in a different manner. The Zeiss seems to be tuned for extracting the maximum amount of detail from a scene, whereas the Sigma prioritizes contrast. The deeper reasons behind this are beyond the scope of this blog, but needless to say, lens design is a complex topic, and adequately describing the performance of a lens is a challenge because of the many variables involved. However, the end result is that Sigma, though a route of their own choosing, has arrived at the popular destination of "sharp" and "can use wide open," and they've done so on a budget compared to the other manufacturers.
This is ostensibly a lens for full frame cameras. You could use it for crop frame, but the size, weight and cost of the lens would be a mismatch. Like the 35mm Art, the price isn't so extreme that it's not unimaginable for the average user. There is the old saw about how serious shooting doesn't happen at 50mm, but it is a flexible focal length that is amenable to many people's shooting styles. It doesn't matter that 24mm is better for landscapes and 85mm is better for portraits; no matter what, the industry is going to sell more 50mm's than either of the other two. So in that regards, Sigma has a home run; they've got one of the best lenses in the business at the product position that tends to sell a lot of units, and they've got the price to drive sales. In other words, at the time of this writing (June 2014) expect supplies to be limited through the summer.
So yes, the Sigma is "good" in a way that is more usable and accessible than how the Otus is "excellent."
But is the Sigma "good" in a way that is "better" than the Canon and Nikon counterparts? For many people, the answer is a very straightforward yes, but if we eliminate price as a variable, then the answer is not so black and white.The Nikon 58mm is not technically perfect, but it does produce a distinct look. This is the same dynamic when comparing the Leica 50mm Summilux f/1.4 against the 50mm Summicron f/2; one is very sharp but the other produces a more distinctive rendering.
There is another term that describes the 50mm Art, and that is "normal." It's normal in the sense that it covers the "normal" field of view, but its also the "new normal" for Sigma. Yes, they did tune this lens to compete with the Otus in terms of performance, but there isn't anything exotic or unobtainium-like in its construction. What made the 35mm Art good is also way powers the 50mm Art, and what will likely make the next Sigma Art lens good as well. In other words, in 2014 we are making a big deal of the performance of this lens, but there's a good chance that many future lenses will be like this, and one day this level of performance will be "normal."
... Normal, that is, for lenses in the $1000 USD range. This is pushing the price point up quite a way ways since the heydays of the Nikon 50mm f/1.4D or the Canon f/1.4 non-L. However, this is a new trend in the industry. Have a look around at how many quality lenses are being introduced at that price point: The Sony 55m f/1.8 for A7r, many of Fujifilm's lenses, and now Sigma, with the 35mm, 50mm and 24-105mm all falling within the $900-$1100 range. This isn't coincidence; its a competitive strategy against Nikon and Canon, who traditionally produce lenses at the high end above the $1500 mark. As a means of drawing customers away from Canon/Nikon, Sigma and the other camera system manufacturers seem to be standardizing around the $800-$1200 price point because it is still somewhat affordable, but more importantly, it makes shopping easier. If this trends persists, it will make decision making a no-brainer for customers; no matter what lens you have now, your next lens will cost approximately $1000 USD regardless of what you chose.
So yes, the Sigma 50mm f/1.4 Art. The new normal.
With thanks to Broadway Camera