70-200 and Nikon D850, mounted on Arca-Swiss foot
The 70-200mm f/2.8 is one of the primary lenses that most professionals and serious amateurs have in their lens arsenals. The Sigma 70-200mm f/2.8 DG OS HSM Sport lens is Sigma's second major version of this lens, and the first of its kind in their "Sports" line.
The nomenclature for Sigma initials is as follows: DG means it's full-frame coverage. The OS means it supports optical stabilization. The HSM means that is has Sigma's "hypersonic motor" for autofocus. As is typical for modern Sigma lenses (Contemporary, Art, Sports), they offer a conversion service to change its mount between Nikon, Canon, Sony, Pentax, and Sigma.
You can see the switches for focus options, focus-limit, optical stabilization, and custom settings from the top to the bottom in the image above. The round button in front of the switches is one of three programmable auto-focus buttons; the others are on top of and underneath the lens.
The focus ring is nearer to the camera body than the zoom ring.
The knurled knob near the top-rear of the lens is for locking the tripod collar.
Lens padded case
Sigma revamped an already-good lens and made it better. Or maybe I got an especially good copy.
I’m mainly interested in resolution and focus speed for this focal length range, and it delivers both. It also has the legendary weather sealing of the “sports” series of lenses and every characteristic of a fully professional lens, including very good optical stabilization. The exterior lens optical surface has a fluorine-style coating to resist oil, dirt, and water.
Sigma’s lens kit also includes a super nice padded case for the lens, a bayonet lens hood with a lock button, and it also comes with a rotate-able tripod collar that has a combination Arca-Swiss (yes!) and conventional ¼-20 tripod thread on the foot.
The tripod collar is rock solid. They include hex keys if you want to remove the foot (the collar stays put). I’d recommend you leave the foot on, since it’s at the proper balance point for the lens. The edges are rounded, so it’s comfortable if you use it as a carrying handle with the camera upside-down. The collar has nice click stops at every 90 degrees, after you loosen the knurled knob.
As a signature of a pro lens, it includes three programmable AF function buttons (you press whichever one is nearest your finger while zooming). You can use these to initiate focus or lock focus; program them using the Sigma USB dock. There’s also the “Lens focus function buttons” assignment in the camera custom controls.
There’s even a programmable focus-limiter switch. Again, use the Sigma USB dock to change its distance behavior.
The lens doesn't change its length as you zoom. It's not even remotely close to being parfocal, in case you wondered.
This is a big, heavy, tough lens. Sigma’s philosophy is that “it weighs what it weighs”. Their prime motivation is optical results and survivability. It weighs almost exactly 4 pounds and is 8 inches long, sans lens hood. I totally agree with Sigma’s philosophy; don’t sacrifice features or quality just for the sake of weight. I know backpackers will wholeheartedly disagree with this philosophy (I used to be a backpacker myself). I think that the correct mantra is “Resolution, quality, light weight; pick any two”.
The barrel is magnesium alloy, and it sports the “E” style aperture which supposedly works better at stopping down while shooting high frame rates. Speaking of the aperture, it has eleven blades, which are rounded (to optimize the bokeh).
It uses 82mm diameter front-mounted filters. I’d skip using any UV “protective” filter on this lens; use its deep lens hood for protection instead. You should always be using the lens hood for better quality photos with all telephotos anyway; there's a lot of glass in this lens. It’s already weather-sealed, so filters aren’t needed for that purpose, either. You’ll probably need to lose the lens hood if you try a polarizer, however; it’s too hard to gain access to rotate it.
I did all of my testing using the Nikon D850. Lesser cameras may show worse resolution and focus speed measurements.
Ironically, this lens didn’t impress me much with the first few test photos I took. Here’s why: the lens needed auto-focus calibration in the worst way. Fortunately, this lens supports the Sigma USB calibration dock. Focus is now perfect at every focal length and at every distance (the D850 AF fine-tune value remains at zero). You can focus calibrate at 4 focal lengths and 4 distances per focal length. Nikon still hasn’t caught on with this feature; they only let you calibrate at a single distance and a single focal length. Blech.
In the resolution charts below, the "exif" data shows the AF tune value of "0". That just means the focus tuning is kept inside the lens, so that the camera body can be left at zero.
My Sigma USB dock calibration settings
I’ll never understand photographers that will pay big bucks for camera gear and never even think about calibrating it. What a shame.
While I had the lens on the USB dock, I went ahead and programmed its “custom” switch settings (C1 and C2). I program the C1 switch to use the “Moderate View” optical stabilization algorithm and the “High Speed AF” algorithm. I program the C2 switch to use “Standard AF” algorithm and “Moderate View” stabilization. When the custom switches are both off, then the lens uses “Standard AF” and “Standard View” stabilization.
By the way, the stabilization “view” you program has no effect on the actual lens stabilization anti-shake capabilities for the photograph. It’s only a viewfinder preference. At least I couldn’t tell any difference with vibration reduction performance (which seemed excellent to me).
It sounds really petty, but my biggest complaint with this lens is the lens cap. It’s very fussy to attach it, particularly if you leave the lens hood on. I’m tempted to get a Nikon cap for it (they fit nicely on it).
I measured the focus speed by setting the lens at 200mm, f/2.8 and minimum focus distance (about 4 feet). I then timed how long it took to focus on infinity (using phase-detect of course) under sunny conditions. I measured 0.36 seconds. I used the “High Speed AF” algorithm for this test. I used “slow-mo” video at 240 fps to review the focusing action (looking at the focus scale).
I found the focus accuracy and repeatability to be excellent. I see no reason yet to switch to a slower autofocus algorithm. Sigma put their “hypersonic focus motor”, which they call HSM, into this lens.
If you’re interested in how fast it focuses, then you’d be foolish not to use their USB dock and program it for the “high speed” focus algorithm. They also have a special “smooth” focus algorithm that’s designed for video use, but it’s the opposite of fast.
I found that on another lens (the Sigma 150-600 C) that the "High Speed AF" algorithm is about 20% faster than the "Standard AF" focus algorithm.
I also tried using Sigma’s TC-1401 1.4X teleconverter (280mm and f/4.0). The same focus test took 0.45 seconds. The teleconverter only slowed the lens down by 25%. I’ll work on a review of their teleconverter later, but (spoiler alert) I found it to be very good with this lens.
I wanted to mention that you have to put the teleconverter onto the lens before you mount it on the camera, or else autofocus won’t work. You have been warned. Also, Nikon teleconverters won’t work on the Sigma. Likewise, you shouldn’t put a Sigma teleconverter onto a Nikkor lens. You have been warned. Twice.
Sigma also makes a compatible 2X teleconverter (TC-2001) for this lens; I haven’t tried it. I can go for f/4 but I’d rather not go for f/5.6.
Sigma USB dock calibration settings: TC-1401 + 70-200
The calibration settings for the teleconverter shown above are ALSO saved, separately from the 70-200 calibration settings. The Sigma engineers are clever enough to know the lens focus calibration won’t be the same with and without a teleconverter. Your own settings would, of course, be different from these. I’m constantly impressed with those Sigma engineers; it’s almost as if they photograph stuff themselves, as opposed to my impression of Nikon and Canon engineers.
I don’t have a very scientific method for testing this. I just zoom out to 200mm and try my best to hold the lens steady on a high-contrast target. I got sharp images with 200mm and 1/15 second more than half of the time. This equates to about 4 stops of anti-shake; your own mileage will vary.
Their “Mode 1” is for general hand-held stabilization; “Mode 2” is for panning operations. In both modes, be aware that it takes about 1 second to be in full stabilization mode after you begin focus or half-press the shutter.
Sigma claims 4 stops of stabilization, so I think they’re honest about what their lens delivers. Everybody is different in how they hold their camera, so I don’t think there will ever be a good measure of this specification.
For those who are interested, this lens doesn’t work well for infrared. It has the dreaded hotspot in the middle of the frame.
Vignetting and Chromatic Aberration
The following shots are some details from one of my resolution targets. They give you an idea of the worst case (f/2.8) on full frame.
Chart center with pure white background, 70mm f/2.8
Chart corner. Background definitely not white. 70mm f/2.8
Chart center, 200mm f/2.8
Chart corner, 200mm f/2.8
There is only the barest hint of chromatic aberration; it’s down in the ignorable region. I couldn’t detect any longitudinal chromatic aberration.
Vignetting is what I’d call “medium”. The shots above give you an idea of worst-case corner vignetting (f/2.8). Decide for yourself if this bothers you. You can of course correct for vignetting in your favorite editor.
I quite like the bokeh, but this is something you can’t really put a number on. They’ve done what they can with the rounded 11-blade aperture.
There’s a small barrel distortion at short focal lengths and really tiny pincushion at the long focal lengths. There’s not enough to bother with, in my opinion.
I found the resolution-versus-focal-length trend to be the same as I have read on other web sites. It’s weakest at 135mm, but that’s not to say it’s “weak”. You’ll see below that the results are generally in the category of very, very good.
The meridional (tangent) direction resolution is generally worse across the board compared to the sagittal direction. This is consistent with probably 95% of all lenses. I’m not aware of any other websites that give you resolution separated into meridional and sagittal directions; they just give you “the number”. The two-dimensional plots below demonstrate how to really understand a lens’ resolution characteristics; a single resolution number is basically nonsense. There’s really no such thing as “the edge” or “the corner” resolution; it’s typically changing all along each edge.
To me, resolution above about 30 or 35 lp/mm looks good, so this lens looks really, really good. The extra resolution just means that you can crop to your heart’s content.
As always, I am only reviewing a single lens copy.
I use the MTFMapper program to perform resolution and focus tests, which you can get here.
I have an article about the MTFMapper use here.
My resolution chart size is 40” X 56”. Big charts provide a more realistic working distance; the actual target distance is included in each plot below.
All of my resolution tests are done using un-sharpened, raw-format from my Nikon D850 (45.7 MP). I use live view and contrast-detect focus, to eliminate any concerns about focus calibration. I’m showing the best results from about 10 shots at each focal length and aperture tested.
I halted each resolution test after stopping down to f/16, because the diffraction effects ruin the resolution beyond this aperture. Even f/16 starts the resolution plunge, but sometimes you need the depth of field. The lens stops down to f/22, if you really need it.
70mm f/2.8 MTF50 lp/mm resolution
These resolution results are first rate. I show the results separated out into both sagittal and meridional directions across the whole FX image sensor (Nikon D850). The center peaks at about an MTF50 of 62 lp/mm or 2962 l/ph. Let me repeat: that’s at f/2.8.
The usual 70mm MTF contrast plot, but actual measurements
The contrast plot above (70mm f/2.8) shows how lens resolution is usually depicted, except MTF contrast plots from most manufacturers are “theoretical performance” without considering the camera sensor. This plot is from the actual measurements on the camera sensor.
You can tell that astigmatism is fairly minimal, since the meridional and sagittal plots track each other pretty well.
70mm f/4.0 MTF50 lp/mm resolution
The center peaks at about MTF50 70 lp/mm or 3346 l/ph.
70mm f/5.6 MTF50 lp/mm resolution
70mm f/8.0 MTF50 lp/mm resolution
70mm f/11.0 MTF50 lp/mm resolution
70mm f/16.0 MTF50 lp/mm resolution
102mm f/2.8 MTF50 lp/mm resolution (close enough to 100mm)
102mm f/2.8 MTF contrast
102mm f/4.0 MTF50 lp/mm resolution
102mm f/5.6 MTF50 lp/mm resolution
102mm f/8.0 MTF50 lp/mm resolution
102mm f/11.0 MTF50 lp/mm resolution
102mm f/16.0 MTF50 lp/mm resolution
135mm f/2.8 MTF50 lp/mm resolution
135mm f/2.8 MTF contrast
135mm f/4.0 MTF50 lp/mm resolution
135mm f/5.6 MTF50 lp/mm resolution
135mm f/8.0 MTF50 lp/mm resolution
135mm f/11.0 MTF50 lp/mm resolution
135mm f/16.0 MTF50 lp/mm resolution
200mm f/2.8 MTF50 lp/mm resolution
200mm f/2.8 MTF contrast
200mm f/4.0 MTF50 lp/mm resolution
200mm f/5.6 MTF50 lp/mm resolution