Sigma 18-35mm f/1.8 DC HSM "A"
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Lab Test Results
June 14, 2013
by William Brawley
SPECIAL NOTE: As you'll see below, this is an incredible lens at an amazing price vs. the competition. We believe it will be severely backordered.
Accordingly, we've set up the special pre-ordering links below from two of our most-trusted affiliate partners. Note that neither will charge your credit card until the lens ships, you can cancel your pre-order at any time, and if the lens ships and you decide you don't want it, you can return it with no hassle.
Bottom line, if you even think you might want this lens any time soon, you should place a pre-order immediately to get a place in line. Otherwise, it could well be many months before you'll be able to buy one. Here are the links for the various lens mount models, purchases made through them help keep these reviews coming:
And now back to our regularly-scheduled review...
The Sigma 18-35mm ƒ/1.8 DC HSM "A" lens is a wide-angle to standard zoom lens designed for APS-C "crop"-sensor cameras. Part of Sigma's new "Art" series, it is the first zoom lens anywhere to feature a constant ƒ/1.8 aperture. This gives shooters the ability to not only photograph in much darker conditions but also produce a much shallower depth of field, compared to all other zoom lenses that only open up to ƒ/2.8 or smaller. This makes it especially noteworthy among its competitors.
On a camera with a 1.5x crop factor, the Sigma 18-35mm ƒ/1.8 features an approximate field of view range equivalent to a 27mm-52.5mm on a 35mm camera, making it a versatile all-around lens that encompasses a useful range of wide-angle to normal focal lengths. As mentioned, unlike a lot of zoom lenses for APS-C cameras, the aperture of the Sigma 18-35 stays constant throughout the zoom range with maximum and minimum apertures being ƒ/1.8 to ƒ/16, respectively.
The lens does not feature image stabilization like some of its rivals (e.g. Canon 17-55 ƒ/2.8 IS USM), but the wide ƒ/1.8 aperture helps compensate for that allowing shutter speeds more than twice as fast in low light. The Sigma 18-35 has separate zoom and focusing rings, as well as marked focal lengths (18, 20, 24, 28, 35mm) and a focusing scale.
The Sigma 18-35mm ƒ/1.8 DC HSM "A" lens ships with lens hood, front and rear caps and a soft case. Sigma is pricing this lens very competitively at a street price of just $799 for Canon, Nikon and Sigma mounts, with Sony and Pentax models coming soon. As you'll see below, this is an incredibly aggressive price when compared with competing models from the camera makers. (And there really is no competition, when it comes to the ƒ/1.8 maximum aperture.)
*Note that this lens review is currently based on a pre-production model.
New: Check out some real-world sample photos taken by our lens specialist Rob over our Flickr page!
This is an amazingly sharp lens, even wide open at ƒ/1.8, which is typically not the case with very wide-aperture lenses. At 18mm and ƒ/1.8, the Sigma shows very little corner softness and a good portion of the center and middle of the frame are very sharp indeed. As we've seen time and again, very wide-aperture lenses (> ƒ/2.8) can often show significant corner softness when used at their widest apertures, but the Sigma 18-35 not one of them. In this respect, it beats even many fast prime lenses in its focal length range.
Stopping down at the wide end, between ƒ/2 and ƒ/2.8 appears to be the sweet spot, in terms of center sharpness. At ƒ/2.8, the overall frame appears extremely sharp. Even stopping all the way down to ƒ/16, diffraction limiting is really quite minimal. As you can see in the Blur Index graph at right, variances in sharpness remain minimal at all apertures as you zoom out to 35mm. Even at 35mm at ƒ/16, diffraction effects are not significant. Overall, sharpness results for this lens are nothing short of stunning.
The Sigma does quite well in controlling chromatic aberration. As expected, we saw more CA at the wide-angle focal lengths, but it drops significantly in both the corners and across the frame as you zoom to 35mm. At 18mm, the corners show two times more CA compared to the average across the frame(about one 600th of a percent of the frame height vs. a 300th), but as you zoom to the longer focal lengths, the difference between the corners and average shrinks appreciably.
We also see well-controlled vignetting with the Sigma 18-35mm lens. While there is still some vignetting at apertures wider than ƒ/4, it's not extreme and the amount of vignetting is consistent across all focal lengths. At all focal lengths, there's about a half to just shy of two-thirds of a stop of light loss. Vignetting decreases notably when you hit ƒ/2.8 with less than or equal to a fourth of a stop of light loss. When stopped down to ƒ/4 and beyond, vignetting at all focal lengths is barely noticeable.
Just like CA and vignetting, distortion is nicely controlled, although not eliminated altogether. We see a bit of barrel distortion at focal lengths wider than 24mm, but less than we might normally expect from a zoom. At 18mm, there is about 0.5% of barrel distortion in the corners while only 0.3% for the average across the frame. At 24mm, the average distortion approaches 0%, yet we start to see a bit of pincushion distortion starting to appear in the corners. Oddly, as focal length increases from 24-35mm, the average shows a very slight increase in overall barrel distortion, while the corners experience a noticeable increase in pincushion. However, the pincushion distortion at 35mm is not extreme – we measured less than -0.5%.
The odd behavior of distortion that's positive (barrel) overall but negative (pincushion) in the corners is doubtless due to the correction built into the lens design: It's not uncommon to see second-order distortion that varies from pincushion to barrel across the frame on highly-corrected lens designs, usually at wide-angle focal lengths. (We've also heard this called "mustache distortion", because straight lines near the edge of the frame are sometimes rendered in a wavy, mustache sort of shape.)
The Sigma 18-35mm lens autofocuses very quickly, racking from closest focus to infinity in about 1 second, thanks to its electronic Hyper Sonic Motor. In basic usage, autofocus was fast, locked onto targets easily and didn't hunt while focusing. Small changes in focus happen very quickly and the AF motor is almost silent.
In the pre-production model of the lens we tested, we were warned that some of the features of this lens were not finished yet. According to Sigma, the firmware in the lens we tested was not finalized, and therefore AF speed and accuracy might not be as precise as in the final retail version. When our lens specialist Rob took the lens out for a spin around town, he did in fact note some focusing bobbles, particularly at ƒ/1.8. Given that Sigma had warned us that the lens's firmware wasn't final, we'll wait for a production sample before commenting on AF performance.)
Nevertheless, this new lens is part of Sigma's Global Vision design and is compatible with the new Sigma USB dock, so you can customize any AF microadjustments your copy may need. To see the new Sigma USB Dock and software in action, check out this video from Sigma: http://vimeo.com/64665246.
This lens isn’t specifically built for macro, with maximum magnification of 0.23x and a minimum close-focusing distance of around 11 inches.
Build Quality and Handling
The build quality of this lens seems excellent. Sigma touts the use of "Thermally Stable Composite" material for most of the lens construction to reduce weight while increasing the lens's durability. The lens feels very solid and, despite Sigma's claim of weight-saving construction, there's a nice heft to it: 809 grams (1.78 lbs). The lens mount and surrounded area are made of metal.
The lens features an aspherical element with "Special Low Dispersion" glass that helps compensate for aberrations. It also features Sigma's "Super Multi-Layer Coating" to help reduce flare and ghosting and increase contrast. A 9-blade rounded diaphragm aperture contributes to nice, creamy background blur or "bokeh."
Despite Sigma alerting us that the prototype's fit and finish aren't up to final production standards, the zoom and focus rings are buttery smooth, with nice, wide rubbery-ribbed grips. The zoom ring is very well dampened, with a firm feel when rotating the ring that stops short of seeming stiff. There's about 45 degrees of rotation from 18 to 35mm, a pretty short throw, but it didn't feel tweaky in use. The barrel doesn't extend while zooming, so there is no chance of zoom creep. The focusing ring at the far end of the lens has about 120 degrees of rotation and will rotate continuously, although there are soft stops indicating the approximate near and infinity focusing limits. The focus indicator ring will rotate slightly past the close and infinity focusing mark indicated on the lens. The zoom ring is about 3/4 inch wide, and the focus ring is larger at about an inch. There's also a nice array of fine non-rubbery ridges on the underside of the lens barrel between the rings for added grip. The lens also features a mechanical manual focusing switch, located on the left side of the lens barrel.
The matte black finish of the lens gives it a nice stealthy look, which is nice, given that this lens is not that stealthy in size. It's not a compact lens by any means, with an overall length of 4.8 inches. The petal-shaped lens hood adds almost another 2 inches in the length. Size wise, the lens is similar in length to a Canon 16-35mm ƒ/2.8L or 17-40mm ƒ/4L lens, but slightly skinnier.
The included matching black plastic lens hood also feels very solid and locks into place with light yet satisfying and secure snap. The front of the lens accepts large 72mm filters, and the front element does not rotate during focusing or zooming, facilitating the use of filters such as circular polarizers.
There are a nice handful of alternative lens to the Sigma 18-35mm ƒ/1.8 lens, although at this time there aren't any that come close to matching the combination of specs and price of the Sigma.
The prime competitor to this lens for Canon users would be Canon's own EF-S 17-55mm ƒ/2.8 IS USM lens. It features a larger range of focal lengths, going all the way to 55mm, as well as featuring image stabilization. The downsides are that is has a narrower maximum aperture at ƒ/2.8 and a much higher price tag with a current street price of around $1200.
For Nikon users, there is the similarly-spec'd 17-55mm ƒ/2.8G ED-IF AF-S DX lens, featuring an identical focal length range, ƒ/2.8 aperture and Vibration Reduction, but again with a much higher price at $1400 and the same smaller maximum aperture. Nikon also has another option with the 12-24mm ƒ/4G IF-ED AF-S DX zoom lens, featuring a wider, yet shorter zoom range, going all the way down to 12mm but stopping at 24mm. Also, compared to the ƒ/1.8 aperture of the Sigma lens, the Nikon 12-24 DX lens features a paltry ƒ/4 constant aperture, more than two stops slower. And even with these limitations, this lens is more expensive than the Sigma, coming in at $1000.
Another alternative is the Tamron SP AF 17-50mm ƒ/2.8 XR Di II LD, which has a similar focal range, but again only an ƒ/2.8 aperture. It is significantly less expensive at $500. There is also an image stabilized version of this lens for $650. Either of these lenses are decent enough wide zooms, but they aren't remotely in the same performance realm with the Sigma.
The Sigma 18-35mm ƒ/1.8 DC HSM "A" lens packs a big punch in features and image quality without a big punch to the wallet. Shockingly sharp images at all apertures, even at ƒ/1.8, with excellent flatness of field and good control over chromatic aberration, distortion and vignetting make this lens a no-brainer for users of APS-C cameras looking to upgrade from their kit lens. The Sigma 18-35mm ƒ/1.8 DC HSM "A" is not only by a wide margin the best constant-aperture/wide-aperture wide-angle zoom lens we've ever tested, it easily beats most prime lenses within its focal length range. Furthermore, the Sigma 18-35mm ƒ/1.8 DC HSM "A" has excellent build quality, with smooth zoom and focus actuation and a nice, hefty heft to it that brings to mind the feel of high-end professional-level zoom lenses. With a super-fast constant ƒ/1.8 aperture that produces surprisingly great images, packaged with excellent build quality, and at the same time having a price that dramatically undercuts the competition, the new 18-35mm ƒ/1.8 DC HSM "A" is sure to become a top seller for Sigma. (As we said at the top, if you want one of these any time this year, you'd better get in line quick.)
New: Check out some real-world sample photos taken by our lens specialist Rob over on our Flickr page! Note, though, that the prototype's AF firmware isn't final, so most of the samples are a little soft. They're useful for evaluating CA and distortion, but we'd suggest not judging sharpness from them. Our very carefully (manually) focused lab shots show the lens to be quite sharp, with an amazingly flat field for such a large-aperture lens, let alone a zoom, but we don't feel that the real-world examples show this particularly well.
For some more samples from someone who evidently had more time with a prototype than we did, check out this collection from a Korean site. They don't have any full-res samples available, but there's some good examples of bokeh at various apertures. The quick story on it is that bokeh at f/1.8 looks very nice and creamy, but as you stop down it becomes less attractive. Notice the hard edges on out of focus background objects in the examples shot at f/8.
Our VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.
As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.
Sigma 18-35mm f/1.8 DC HSM "A" User Reviews
10 out of 10 points and recommended by larslentz (4 reviews)sharp, low-cost
I get incredible image quality from this lens. While I cannot zoom in as it is only 17-35 in range, that doesn't matter because the sharp images I get are worth it. It does weigh a bit more than other lenses, but it has great construction and the weight of it conveys that feeling when you're shooting with it. The sharpness sweet spot starts at about f/2.8, but even wide open at f/1.8, I get excellent results. I would highly recommend this lens as a replacement for any kit lens. It is made only for APS-C cameras, so keep that in mind if you have a full-frame camera it will not work well. By having the f/1.8 maximum aperture, it levels out the playing field for APS-C cameras and puts them on par with a full-frame cameras using f/2.8 lenses. This is due to double the light being let in by this f/1.8 lens. Overall, this is a fast, sharp, well-made lens and you would benefit your photography to purchase it!reviewed May 23rd, 2015 (purchased for $799)
9 out of 10 points and recommended by Nikonuser (5 reviews)Sharp, price f1.8Weight
I replace my Tamron 17-50 f2.8 by this lens and I do not regret. It is sharp and on my D7100 it is a perfect match. The only negative comment, it is a big and heavy lens compare to my Tamron.reviewed May 13th, 2014 (purchased for $850)
10 out of 10 points and recommended by nicohoho (1 reviews)cheaper, solid, sharp, openDidin't find yet! Maybe not "tropicalized"
One of my best lens, even if clearly not the most expansive one. You can shoot at stars and get sharp stars everywhere, even in the far corners at f/1.8 (not exactly punctual, but very close to and better than whatever I saw before at such aperture). It is sharper than the Zeiss Distagon 25mm at f/2.8. I also realize that the contrast I get from pictures with this lens is larger than with all my other lenses. This clearly appears when I develop my picture in Lightroom v.3.6: the "black level" that is set by default at 5 (and is usually fine) must be set near zero. The focal length may seem too short for portraits, but I got great shots (I modestly think) with this Sigma 18-35 on my D300 (full-length portrait particularly). Indeed at full aperture, the DOF is only a few inches at one meter. For me the bokeh is quite nice, even if the light spots are a bit triangular in the corners.reviewed December 15th, 2013 (purchased for $900)