|Nikon D7200 and Sigma 17-50mm f/2.8 HSM OS|
Constant f/2.8 zooms are always popular, especially when they are as small as these third-party alternatives. So, is the Sigma 17-50mm OS the proverbial walk-around, go-anywhere normal-zoom that so many photographers are looking for?
April 2015 Update: Additional information about compatibility with different Nikon bodies added.
tl;dr: This lens does not display the infamous "scroll bug" and accelerated battery drain when mounted on a D7200 or D5500.
Body and Design
|Sigma 17-50mm f/2.8 OS on Canon 70D|
The Sigma 17-50mm seems unusually small compared to other f/2.8 normal-zooms. It's dwarfed by its Canon counterpart, the EF-S 17-55mm f/2.8 IS USM, as well as the Nikon 17-55mm f/2.8G ED-IF AF-S DX. Compared to the first-party lenses, the Sigma is smaller in all dimensions; shorter, narrower and lighter. Surprisingly, the Sigma takes 77mm filter rings, just the same as the other two lenses. (Its Tamron VC counterpart uses 72mm filters, whilst the original Tamron 17-50mm uses 67mm.)
|Left: Canon 17-55mm f/2.8 Right: Sigma 17-50mm OS|
Thankfully, the Sigma is more like the Nikon, rather than the Canon, in that a hood comes supplied with the lens (not depicted) instead of being an extra to be charged for. (Despite being a constant f/2.8 lens, the EF-S 17-55mm f/2.8 is still not a "L" lens, hence, no petal hood is included.) A carrying case is also included with the Sigma. If you live in Canada, you get the bonus of having a 7 year warranty against manufacturer's defects (possibly the longest in the industry), compared to the 4-year warranty offered in the U.S.
Design-wise, it's difficult to avoid a sense of déjà vu when holding the Sigma 17-50mm OS, especially if you've used the Tamron 17-50mm. How venerable is the Tamron? It dates back to the D200 days, and is still a relevant lens today. Except for the wider filter ring, both lenses are roughly of equal bulk and proportions:
|The Tamron 17-50mm f/2.8, non-BIM version|
However, there is an build-quality difference between the two lenses. The Sigma feels a bit sturdier and and has less barrel-wobble when it is extended. That said, the design and build quality aren't up to Sigma's more recent Global Vision line of lenses. Compared to the 18-35 f/1.8 DC HSM, it's an ostensible step down in construction (not to mention size, weight and price).
One feature that does betray the older design of this lens is that the autofocus can't be over-ridden like on a true Canon EF or Nikon AF-S lens. The focus ring turns during AF operation, and has to be switched to full manual for manual focusing. Again, this is not unlike the Tamron 17-50mm. Eventually, there may indeed be an "ART" version of this lens, but considering that that 17-50mm OS was launched just before the global revamp, this current version will be a stalwart on store shelves for a few years more.
The optical stabilization (OS) part of the lens works quickly and effectively. Sigma says that the system is good for four stops of stabilization; 3-is more realistic for most people, and if you adjust your shooting as if they lens could only give you a two-stop advantage, shots will come out rock solid the vast majority of the time. As you would expect for a lens at this price range, the stabilization is either "on" or "off"; it does not allow for a second panning mode where only vertical motion is corrected.
The OS function operates at a fairly silent level, and does produce smooth, stabilized video for simple still shots. Without the dedicated panning mode, the lens (like nearly all other IS/VR lenses) "grabs" onto the point of focus tightly, causing a stuttering effect during pans. On a related note about video operation, turn off the autofocus. The AF mechanism is not a true AF-S/ USM mechanism and focuses nosily and not particularly smoothly during video recording.
Overall optical performance is generally excellent, but there are some catches. Like many zooms in this class, it has visible barrel distortion at the wide end, which flattens out to a slight bit of pincushion distortion at the long end of the focal range.
|17mm, on Canon 70D|
However, it wouldn't be Sigma if we didn't talk about sample variation. The image below at 50mm has a bit of backfocus to it. Uncorrected, this was consistent throughout different focal lengths image distances with the tested sample. However, to be fair, both the Canon 70D body and this lens were retail demonstration units.
There are two bugs to watch out for if you are using this lens on the Nikon D7100, D5300 and D3300. The problem stems from the fact that the OS image stabilization system doesn't work as intended with these cameras; after taking a shot, it remains active for up to a minute. In all other ways, the lens is compatible with these cameras. Just to be clear, this applies even to later-issue units of the 17-50mm, with boxes marked "Nikon D5300 compatible." Well, it is... almost.
There are two consequences to this. The first is increased battery drain, and the second is that the mulch-selector has to be tapped repeated to navigate during image reviewing instead of the usual press-and-hold operation; hence the term "scroll bug"... or more correctly "playback scrolling bug." (See this DPReview thread for more details.) The root of the issue is with Nikon, as this behaviour didn't manifest on the D7000 or older cameras; something in the D7100 firmware is new or different.
Curiously enough, the Sigma 17-50mm is fully compatible with the Nikon D7200 and D5500; image review scrolling works as it should. In summary:
- Fully Compatible with: D3200, D5100, D7000, D5500
- OS/SCroll Bug with: D7100, D5300, D3300
Sigma 17-50mm OS vs Nikon 17-5mm f/2.8 vs Canon 17-55mm f/2.8 IS
When compared to either of the Canon and Nikon counterparts, the Sigma is cheaper, smaller and generally offers better value for the money. As a normal zoom, its the everyday walk-around lens that many people are looking for for their 60D's, 70D's and D7000's or D7100's. The size and weight of this lens balances appropriately on these bodies, where as the Nikon and Canon versions tend to overwhelm their own camera bodies. Out of all these three lenses, only the Nikon is truly a professional-grade lens. Even though it lacks image stabilization, its build quality and optical performance are enough to distinguish it from the others. Conversely, for non-paid work, the difference between the Nikon and the other lenses isn't enough to justify the price.
Sigma 17-50mm f/2.8 OS vs Tamron 17-50 f/2.8 vs Tamron 17-50 f/2.8VC
|Left: Sigma 17-50mm OS Right: Tamron 17-50mm non-BIM|
Compared to the either of the Tamron 17-50mm lenses, the Sigma makes a compelling case in that it has (slightly) better build quality and an image stabilization system that operates faster with less noise than the VC version. However, the VC version of the Tamron likely has the best overall image stabilization system if shooting speed is not a priority, and the original non-stabilized Tamron 17-50 f/2.8 is optically the best of this trio. The Sigma can't quite match the latter for consistent-across the frame sharpness, but it does have a flatter plane of focus at the wide end compared to the Tamron, and it does control vignetting and chromatic aberrations better, with smoother bokeh.
Here is an image set comparing the Sigma 17-50mm f/2.8 OS vs the non-stabilized Tamron 17-50mm f/2.8 non-BIM (built-in-motor), both Nikon mounts. First, the scene, with the target (water bottle) approximately 2.5 feet away from the camera. Focal length is 24mm. These were shot on a Nikon D7000.
Here are the 100% crops comparing the point of focus and background blur between the two lenses.
|Point of focus: f/2.8|
|Background bokeh: f/2.8|
|Point of focus: f/4|
|Background bokeh: f/4|
|Point of focus: f/5.6|
|Background bokeh: f/5.6|
At the point of focus, the older Tamron is amazingly sharp and contrasty considering that it's the older design of the two. It's the stronger of the two lenses when the aperture is held wide-open or when the focal length is zoomed all the way out. However, the Tamron's bokeh does show a fair bit of outlining, and the overall out-of-focus rendition does not look as smooth. Though the Sigma is the more versatile lens of the two by virtue of its image stabilization, there's a reason why many people with the first-generation Tamron are loath to give it up.
Sigma 17-50 f/2.8 OS vs Sigma 17-70 f/2.8-4 DC Macro OS HSM C
The "C" (Contemporary) version of the 17-70mm f/2.8-4 is a beautifully finished lens, especially considering that it is a consumer-grade item. Build quality and aesthetics are nicer than with the 17-50mm. Optically, the trade-off is with giving up f/2.8 at the long end in return for 20mm of extra focal length. In real world shooting it's not actually that much more reach, and is the equivalent of stepping a few feet closer to your subject. However, there is a difference in perspective at 70mm compared to 50mm, but given the variable aperture nature of this lens and the intended audience, that will likely not matter for the 17-70's intended purpose. As one of the new Global Vision lenses, the 17-70mm "C" is compatible with Sigma's USB dock.
Sigma 17-50 f/2.8 OS vs Sigma 18-35mm f/1.8 DC HSM
Moving in the other direction, the 17-50mm is a bargain compared to its 18-35mm bigger brother. The 17-50mm is lighter and smaller and has the added benefit of optical image stabilization. The headline feature for the 18-35mm, however, is that it does a constant f/1.8mm, albeit with a restricted zoom range. The 17-50mm is a better all-around choice (you can use the OS function for video), but the 18-35mm is unique, and does something that no other APS-C sized lens does: achievable bokeh at moderately wide-angle shooting. The 17-50mm is the better all-around choice, but if you can live with the shorter zoom-range and higher price tag; the 18-35mm is sharper and optically distinctive in comparison.
It is said that professionals don't use f/2.8 normal zooms. There is truth and untruth in that statement. A dedicated landscaper or portrait photographer would naturally use other more mission-specific lenses, but there are a lot of of wedding and event photographers out there that do use normal zooms. All of the advantages that hobbyists see in these lenses apply to working professionals, especially when the conditions are changing and dynamic. An affordable lens with a constant f/2.8 aperture range that also has image image stabilization. What else is there to say? Those three things sell themselves, and they sell the Sigma 17-50mm f/2.8 OS. However, as good as this lens is, it's not really a professional lens. It's just not optically consistent enough, though there is no deal-breaker reason not to use this lens for paid-work other than the middling f/2.8 performance.
With thanks to Broadway Camera.