The Sigma APO 120-300mm F2.8 EX DG OS HSM has a new optical design using 23 elements in 18 groups, whereas the previous version used 18 elements in 16 groups. It’s also slightly longer and slightly heavier.
The Sigma APO 120-300mm F2.8 EX DG OS HSM is internal focusing and internal zooming, meaning that the length does not change on focusing or zooming and that the front element does not rotate. While many long telephotos use a rear mounted filter, the Sigma 120-300 uses a front mounted 105mm filter and no provision is made for rear filters. A coated UV filter is available from Sigma for around $100 (the lens does not have a flat filter built in, so the first glass surface is that of the front optical element). A quality 105mm circular polarizer will cost between $200 and $300.
The Optical Stabilization system has two mode. Mode 1 stabilizes in both the horizontal and vertical directions, while mode 2 is optimized for panning and provides vertical stabilization. It can be turned off if desired (e.g. it should be turned off for long exposures with the lens mounted on a tripod to prevent the image from “drifting” during the exposure)
Full time manual focus is available without the need to switch from AF to MF operation. In AF mode there is no distance range limiting switch, the full focusing range being available at all times. There is a distance scale marked in ft and meters, but there are no DOF or IR focus markings.
The tripod mount can be removed if desired, making hand holding the lens a little easier. When mounted 360 degree rotation is available, but there are no click stops at 90 degree intervals such as are found on some lenses of this type.
The supplied lens hood is attached via a bayonet mount. It’s a cylindrical design rather than a “petal” shape and it’s made of plastic. A soft carrying case is also supplied with the lens as a standard accessory.
Lens Construction 23 Elements in 18 Groups Angle of View 20.4-8.2 degrees Minimum Focusing Distance 150-250cm cm / 59.1-98.4in in Number of Diaphragm Blades 9 Mininum Aperture f22 Filter Size (mm) 105mm Maximum Magnifications 1:8.1 (at 200mm focal length) Dimensions (Diameter x Length) 114.4mm x 289.2mm mm/4.5in. × 11.4in. in Weight 2950g / 104oz.
The Sigma 120-300 obviously covers the range from 120mm to 300mm. What may not be so obvious is that like most zoom lenses, the focal length range is slightly different when the focus distance is significantly less than infinity. For example I measured the focal length at infinity for the 300mm setting and it came out very close to 300mm. However with the Sigma 120-300 focused down to around 10ft and the lens set to a nominal 300mm, the actual focal length was around 240mm. This doesn’t really matter except for the fact that you get a little less magnification than you might expect when the lens is close focused. At a focus distance of 30ft I measured a maximum focal length of 273mm and at 50ft this increased to 281mm. As I mentioned, most zoom lenses to this, so it’s not a specific criticism of this lens, but it’s something to be aware of. In general, prime (single focal length) lenses do not do this.
The close focus distance is 1.5m at the 120mm setting and 2.5m at the 300mm settings. The focus ring is in the same position for both of these focus distances, i.e. when the focus ring hits the close focus stop, the focus distance depends on the focal length setting. Maximum magnification of about 0.125x (1/8 life size) is achieved not at the 300mm zoom position as you might first think, but actually at the 200mm focal length setting because you can focus closer at the 200mm setting.
Sharpness at closest focus (300mm focal length, 2.5m distance) is a little soft wide open but at f4 is quite good (pretty much on a par with the Canon 300/4L at the same aperture and focus distance). However due to focal length change on close focus (as described in the previous paragraph), the Canon 300/4L gives about 25% higher magnification.
The Sigma 120-300 doesn’t have a focal range limiter, so if focus can’t be achieved it can cycle between infinity and the close focus distance (1.5/2.5m). I measured the time to focus from infinity to closest focus or from closest focus to infinity at around 0.67 seconds. A complete cycle from infinity to close focus and back to infinity includes a 0.7 second pause at the closest focus distance, make the the “round trip” time just over 2 seconds.
I had no issues with focus accuracy on most shots taken with the Sigma APO 120-300mm F2.8 EX DG OS HSM . I used it with both an EOS 5D (Mk I) and an EOS 7D, in both AF and MF modes. With the EOS 7D I used Live View for manual focusing. MF was not consistently better (or worse) than AF. AF was not always absolutely perfect, but was always well within the typical Canon specification of 1/3 the DOF for f2.8 lenses. With the particular camera bodies I used in these tests there did not seem to be any bias towards front or back focus.
Tracking AF is always difficult to test because it’s hard to find a target that moves at a consistent speed. I did shoot some tracking sequences of moving cars and in general most (but not all) of the images were in acceptable focus. You can feel and hear the AF mechanism moving in small steps. This is in contrast to a lens like the Canon EF 70-200/2.8L IS II USM, where tracking focus is essentially smooth and silent. Except for seeing the focus adjust in the viewfinder, you wouldn’t know the lens was doing anything!
The Sigma 120-300/2.8 has Sigma’s OS (Optical Stabilization) built in. This operates in a similar way to Canon’s IS, Nikon’s VR and Tamron’s VC systems in that it moves internal lens elements in a way designed to compensate for lens movement. Sigma claim that the OS “allows for hand-held tele-photography and the use of shutter speeds approximately 4 stops slower than would otherwise be possible.” There are two OS modes. Mode 1 is for general use and provides both vertical and horizontal stabilization. Mode 2 is for use when panning and presumably stabilizes only on the vertical axis.
It’s always difficult to measure the effectiveness of any optical stabilization system because it all comes down to probabilities and percentages. There’s no standard test, you just have to take a lot of handheld shots with and without IS at a range of shutter speeds and compare the results. At 300mm the “rule of thumb” is that when shooting with a full frame (D)SLR you’ll probably need a shutter speed of 1/300s to have a reasonably good change of a sharp image when the unstabilized lens is handheld. Of course this doesn’t mean you can’t occasionally get a movement blurred shot at 1/1000s or a very sharp shot at 1/75s. It’s just that these are less likely. The same goes for IS. If the IS gave 3 stops of stabilization, you’d expect a good chance of sharp images at 1/75s, but you might get some sharp shots at 1/30s and some blurred shots at 1/250s.
An additional problem is that of defining what a “sharp” shot is. Few hand held shots will be as sharp as a shot taken using a heavy duty tripod and a remote release. However if you define sharp as something along the lines of slight blurring that probably wouldn’t be noticeable in an 11×14 print, you have a more reasonable working definition.
Looking through many images (well over 100), my guesstimate is that the Sigma OS system is routinely capable of yielding sharp images with shutter speeds 2-3 stops slower than without it. If the photography Gods are with you, you might get to 4 stops slower, though it’s not likely very often and certainly not something to depend on.
The bottom line is that the OS is very useful indeed when using the Sigma 120-300 hand held. It’s a fairly heavy lens (2.58kg/6.5lbs), so it’s not easy to hold steady at eye level for long lengths of time. That additional 2-3 stops of stability make it a much more useful lens than it would otherwise be. If you happen to be lucky enough to get 4 stops, it’s a bonus!
Vignetting with the Sigma 120 was slight, even on full frame. With the lens mounted on an EOS 5D I measured slightly over 1 stop of corner darkening at 300mm and slightly under 1 stop at 120mm. On an APS-C crop sensor body vignetting is negligible at all focal lengths. Even on full frame the vignetting is small enough that it can be easily and effectively corrected, though it’s small enough that in many cases correction might not even be necessary.
Chromatic aberration was very well controlled. Even at the edge of the image there was little evidence of color fringes, even on very high contrast transitions such as the edge of the moon – a fairly severe test for chromatic aberration.
Distortion is low as would be expected for a long telephoto lens of this type. At 120mm there is no observable distortion and at 300mm there’s very slight pincushion (less than 1%), and it’s unlikely anyone would even notice it unless looking at a test chart.
Sharpness is very good at all focal lengths. In the center of the image there’s a very slight in sharpness as the lens is zoomed from 120 to 300mm, and stopping down doesn’t make an significant difference in center sharpness at any focal length.
The corners of the full frame image are a little softer than the center, especially wide open and more so at 300mm than 120mm. Stopping down does improve the corner sharpness and at all focal lengths an aperture of f5.6 seems to yield peak center, corner and edge sharpness. At f8 and smaller apertures you detect a slight softening coming in as a consequence of diffraction effects if you look closely at resolution test charts, though the lens is still very sharp at f8 and f11.
Corner sharpness more closely approaches center sharpness when the lens is used on an APS-C crop sensor camera of course.
Comparing the Sigma 120-300 OS with the Canon EF 70-200/2.8L IS II USM, I’d say that over their overlapping 120mm to 200mm focal length range, at the same aperture the two lenses are about equal in sharpness in the center of the frame, but the Canon lens has an advantage in the corners of the full 35mm frame, especially at 200mm.
Compared to the Canon EF 300/4L at f4, the Sigma 120-300/2.8 wasn’t quite as sharp when shot wide open at f2.8, but when stopped down to f4 sharpness improved and the two lenses showed very similar levels of sharpness across the frame.
The ability to work well with 1.4x and 2x TCs is something everyone looks for in a telephoto lens. The big advantage of f2.8 lenses in this respect is that autofocus is retained on all (D)SLR systems, even with a 2x TC which results in a lens aperture of f5.6. In this regard the Sigma 120-300/2.8 OS becomes:
Which TC? Well, I’m sure that Sigma would say that the best choice would be the Sigma 1.4X Teleconverter EX APO DG and the Sigma 2.0X Teleconverter EX APO DG, and they might well be right. Their own TCs should be the best match for their own lens.
However, I had neither of the Sigma TCs available, so I used my Canon TCs instead. These are the EF 1.4x and EF 2x (Mk I versions). Both fit the Sigma 120-300/2.8 without any problems and appear to be fully compatible. AF is retained and the correct focal length and aperture are reported to the camera.
Sharpness at 420mm with the Canon 1.4x TC was quite good, even with the lens wide open and at 600mm with a 2x TC sharpness was acceptable, though it’s clearly not as sharp as without the TC and not as sharp as a good 600mm prime lens. With the 2x and the lens set to 120mm (=240mm), sharpness was good, even wide open, as can be seen from the image on the left.
Comparing images shot at 420mm and 600mm with those from a Canon EF500/4.5L prime lens, it was clear that the images from the Canon were sharper (as you’d expect) in the center and significantly sharper in the corners, with APS-C results being slightly better than full frame for the corners. However, if you were not printing larger than 8×10 (or maybe 11×14 if stopped down) and if you applied appropriate sharpening in Photoshop, the difference in the print might not be obvious.
Again though, let me state that I was using the Canon EF 1.4x and 2x Mk I TCs in this test. Results with the Sigma 1.4x and 2x may be different.
Since a fast lens like the Sigma 120-300/2.8 has applications as a portrait lens, where smooth background blur is particularly desirable, inevitably there will be photographers who are concerned about “Bokeh” or the quality of the out of focus image. Bokeh is difficult to describe and even more difficult to quantify since it changes with focus distance and degree of defocus. All I can really say is that in dozens of shots I was not troubled by the appearance of any of the out of focus regions. They generally seemed fairly smooth. I’ve posted a few sample shots on the right. The Sigma 120-300/2.8 OS makes an excellent portrait lens (as long as you can deal with the weight).
There are really no direct competitors for the Sigma 120-300/2.8. Alternative lenses covering a similar range tend to be much slower (e.g. 70-300/4-5.6 or 100-400/4.5-5.6). Nikon have an optically stabilized 200-400mm f/4G ED, AF-S VR-II , but it’s a stop slower and at $7000, more than twice the price. Canon have a 200-400/4 with built in 1.4x TC in development, but there’s no work on when it will be available or what it will cost (my guess is over $8000).
Perhaps the nearest competitors might be the 70-200/2.8 lenses, though obviously they don’t have the telephoto reach of the Sigma 120-300/2.8
There are, of course a number of fixed focal length 300mm f2.8 lenses:
The Sigma APO 300mm F2.8 EX DG is smaller ( x 214 mm/4.7 × 8.4 in) and lighter (2400g / 84.7oz.), but lacks any optical stabilization. Street priced at $3400, it’s $200 more expensive then the 120-300/2.8 zoom ($3200)
The new Canon EF 300mm f2.8L IS II USM is also shorter and lighter (5.0 × 9.8 in, 82.9 oz. / 128 × 248mm, 2350g), but much more expensive at around $7300.
The Nikon 300mm f/2.8G ED-IF II AF-S VR-II is slightly shorter (10.5″ × 4.9″ / 267mm x 124mm) and slightly lighter (102.3 oz / 2900g) but at $5800 it’s also $2600 more expensive.
The Sigma APO 120-300mm F2.8 EX DG OS HSM is an unexpectedly good lens. Typically long range zooms aren’t as good as equivalent primes, but this lens probably comes pretty close. It’s well built, fast, optically good and the stabilization system is effective. Most remarkable is the price. At around $3200 nobody can call the Sigma 120-300/2.8 cheap, and it would be hard to even call it “affordable” for most people, yet when compared to the price of the current Canon 300/2.8L IS II USM ($7300) or the Nikon 300mm f/2.8G ED-IF II AF-S VR-II ($5800), it seems like a positive bargain. It’s even $200 cheaper than Sigma’s own APO 300mm F2.8 EX DG (which doesn’t have Optical Stabilization).
Performance with the Canon TCs was pretty good. Some softness at 600mm with the 2x, but that’s to be expected. Still quite usable for many applications but not as critically sharp as a 600mm prime lens would be expected to be.
The ability to zoom could be very useful in situations such as sports photography where the distance from the action can quickly change. It’s probably slightly less important for nature photography where most of the time you’re zoomed out all the way. but it’s still nice to have. The Sigma 120-300/2.8 is even very usable as a portrait lens, especially on a full frame camera.
One slight question mark might be the AF performance relative to something like the Canon EF 300/2.8L IS II USM when used with a high performance body like the EOS-1D X or 5D MkIII. I didn’t get the opportunity to do this test but I suspect that the Canon combination might give better tracking AF under difficult conditions. With the 120-300/2.8 on an EOS 5D, the 5D frame rate is slow and the AF tracking of the camera isn’t the best so though I didn’t get perfect tracking of moving subjects, it’s wasn’t a very good test of the lens’ ability.
The weight might be something of an issue for extended handheld use, but that can be said of the fixed focal length 300/2.8 lenses too (though they are in general slightly lighter). I found that I could handhold the lens OK, but the use of a monopod made it much easier, especially when shooting for any length of time.
Overall I have to give the