Sigma 70-200mm 1:2.8 EX DG OS HSM Review
Studio Tests - APS-C format
The 70-200mm F2.8 OS puts in a decent performance on APS-C format. As usual it benefits from the expected advantages of a full-frame lens on the smaller sensor, i.e. minimal distortion and vignetting, and chromatic aberration is also extremely low. Sharpness results are impressive at the short end, but somewhat less so at 200mm.
Sharpness results on APS-C are mixed, and slightly complex in character. At 70mm F2.8 the lens is decently sharp in the center, but slightly softer towards the corners. It improves dramatically on stopping down to F4; there's also evidence for a slight focus shift on stopping down, with the measured sharpness slightly lower in the center than towards the edge of the frame; best results are obtained at F4 - F8. Wide open at longer focal lengths, the soft region spreads further into the frame, until at 200mm only the very center is critically sharp, and most of the frame is somewhat soft. Again though the lens improves substantially on stopping down, with best results from F5.6 - F8.
Chromatic aberration is exceptionally low. If you look really closely there's a tiny bit of fringing at the corners, but it probably won't be much of a problem in normal use.
We consider falloff to become perceptible when the corner illumination falls to more than 1 stop less than the center. As we'd expect for a full-frame lens on APS-C there's simply nothing to be concerned about here at all.
Distortion is extremely low, from 0.5% barrel at 70mm, through neutral around 85-100mm, to -0.6% pincushion at 200mm. This is absolutely nothing to worry about, as it will be essentially imperceptible in normal use.
Third party lenses have something of a reputation for less-than-neutral color balance, so here we measure any color cast introduced by the lens in comparison to the camera manufacturer's 50mm lens (generally considered a good standard for neutrality).
In this test, the camera is pointed towards an evenly illuminated white wall, and light entering the lens then completely diffused using an 'Expodisc' white balance filter. A custom white balance is taken using the 50mm lens (in this case the Canon 50mm F1.4 USM), then exposures made using the 50mm and the lens under test (in this specific comparison we've also included the Canon EF 70-200mm F2.8 L IS II USM). The RGB values from the center of the frame are reported (measured as an 11x11 average).
|Canon EF 50mm F1.4 USM
(188, 188, 188)
|Sigma 70-200mm F2.8 OS
(175, 177, 176)
|Canon 70-200mm F2.8 IS II
(182, 182, 183)
The differences between these lenses are very small indeed; both 70-200mms are very close to being as neutral as the 50mm F1.4. The Sigma shows a tiny green shift, whereas the Canon 70-200mm F2.8 IS II has the slightest of cool casts. Neither are likely to count as remotely significant in real world use.
Specific image quality issues
As always, our studio tests are backed up by taking hundreds of photographs with the lens across a range of subjects, and examining them in detail. This allows us to confirm our studio observations, and identify any other issues which don't show up in the tests. In this section we look at issues of specific interest to APS-C users.
Softness wide open at 200mm
The most problematic result to emerge from our studio testing is apparent softness at 200mm, especially when the lens is shot wide open at F2.8. The example below shows what this looks like in practice for a 'brick wall' shot, with 100% crops from the center, lower edge and corner of the frame (using the Canon EOS 7D as the test camera).
At F2.8 the center shows lots of fine detail, but is a little low in contrast; however the edge and corner crops are somewhat soft. The lower edge sharpens up nicely in stopping down to F5.6, with the corner following at F8 (although at this point the center is losing a little of its bite due to the onset of diffraction).
As usual, we've also gone through hundreds of sample shots to see what this looks like in practice with arguably more typical subjects for this kind of lens. With the more usual three-dimensional subjects, such sharpness issues often become less important; the in-focus regions may well be 'sharp enough', especially when shooting at higher ISOs when detail is being lost to noise and noise reduction. In addition, there's not necessarily anything important in focus in the softest regions of the frame anyway.
|200mm F2.8, Canon EOS 7D (ISO 400)||100% crop (rightmost rider)|
|200mm F2.8, Canon EOS 7D (ISO 200)||100% crop|
Naturally you can always pull a bit more out of the image file by careful processing of the raw. Here we've corrected the residual lateral chromatic aberration in Adobe Camera Raw (+10 Red / Cyan), followed by local contrast enhancement in Photoshop (Unsharp Mask with Amount = 5, Radius = 50, Threshold = 0) and finally Smart Sharpen (Amount = 180, radius = 0.8). This brings a considerable improvement in the rendition of fine detail.
|200mm F2.8, Canon EOS 7D (raw + ACR)||100% crop|
|classic mormon row barn in jackson wy by summicron|
from on the farm
|Yosemite Falls Midnight Reflection by Jonathan Shapiro|
from -Mirror in the Night Water- (Landscape in Full Colours Only)
Photographer Peter Guttman was given some of Kodak's revitalized Ektachrome 100 film and took over Kodak Professional's Instagram page to share the images he captured.
We sat down recently with top Canon engineers to talk about the EOS R, and the delicate balancing act of experimenting with a new platform and the risk of alienating existing users.
Sony has updated its image sensor spec page and as expected, a few of the chips they make bear an uncanny resemblance to sensors found inside Fujifilm and Panasonic cameras.
This week Chris and Jordan are joined by renowned macro photographer Don Komarechka, who demonstrates a few simple techniques that can improve your macro photos in a big way.
The group that provides Canon users with programs to expand the feature set of their cameras has begun cracking the new EOS R mirrorless firmware.
The Pixel 3 represents another step forward in computational photography for Google's smartphone. We're just getting started with our testing – for now take a look at some sample images, including 'computational Raw' files available for download.
Lens Rentals Founder, Roger Cicala, has given the Canon EOS R one of his signature camera teardowns.
Nikon says firmware version 1.03 "Fixes an issue that in rare circumstances would delay the shutter release or the start of the autofocus operation."
The Kickstarter campaign for Yashica’s digiFilm Y35 camera has produced a wave of complaints about delays in shipping product as well as cameras that don’t work.
Pixelmator today released Pixelmator Pro 1.2 Quicksilver, a major update to its image editing app for Mac.
Although Raw performance of the EOS R is very similar to the 5D Mark IV, Canon's done some tweaking on the JPEGs - take a look at our studio scene to see for yourself.
If you've backed one of the company's crowdfunding projects, the reward will not arrive and you won't get your money back either as Meyer Optik Görlitz's parent company, Net SE, is completely dead.
The importance of APS-C, a future a7S model in development and why customers want two card slots – read our full interview with Sony's Kenji Tanaka.
Google's Super Res Zoom technology uses pixel-shifting methods to achieve zoom results comparable to some optical solutions. Google has published an in-depth explanation on its AI blog.
CyberLink has release the latest version of its photo editing and design program PhotoDirector.
Toy manufacturer Tomy has launched a no-battery-required smartphone printer that is remarkably like the one Holga has been promoting via a Kickstarter campaign but which is already available for $40/£39.
A handful of Sony users have noticed a particular model of SanDisk SD cards is showing errors when used with Sony a7 III camera.
The Fujifilm X-T3's 4K video more than lives up to its impressive specification, making it one of the most capable video cameras we've ever tested.
VSCO has made it easier to find the right presets for your photos with a few interface changes to its smartphone app.
TinyMOS is back with NANO1, an all-new astrophotography camera that's one-third the size of the TINY1 it announced three years ago.
Huawei's latest flagship device comes with the widest range of focal lengths of all current smartphones.
After shaking up the Lightroom ecosystem with Lightroom CC last year, Adobe has released version 2.0 of the cloud-centric photo organizer and editor. We look at new features like People View, how far Lightroom CC has come in its first year, and where Lightroom is headed.
Today, at Adobe MAX 2018, Adobe previewed Photoshop CC on iPad, a full-featured, desktop-class version of Photoshop for iOS.
The weather and has most definitely taken a turn toward fall here, and our shooting opportunities have followed suit. We brought the Canon RF 35mm F1.8 along to a harvest festival of sorts and a few of our usual haunts.
Pennsylvania Governor Tom Wolf has signed House Bill 1346 into effect, which imposes a fine upwards of $300 to drone operators who invade the privacy or harm the physical wellbeing of citizens.
Sigma is a company in flux, but CEO Kazuto Yamaki is undaunted by the upcoming prospect of developing lenses for eight lens mounts. The challenge will be keeping the company's identity along the way.
If you've been meaning to convert all of your old photos, video, and audio to digital formats, but simply lack the time or willpower to get through it all, a new service from Kodak will help you get the job done.
Almost all new cameras include impressive video features, but for the best results you'll often need an off-camera recorder. Chris and Jordan take a look at the brand new Ninja V from Atomos, and explain why it might just be one of the most useful tools you can add to your camera.
Collect allows you to transform 360-degree into a more easily digestible format by transforming it into directed traditional videos.