Sigma 120-300mm f/2.8 DG OS HSM Sports Lens Review

The Sigma 120-300mm f/2.8 DG OS HSM Sports Lens is a physically beautiful lens that delivers also-beautiful image quality even with a wide open aperture. Remarkable is that this lens has the widest max aperture available in any 300mm lens (f/2.8), but still offers a significant 120-300mm zoom telephoto focal length range. The 120-300 OS is heavy, but it is solidly built with a nicely-implemented OS system to keep your handheld images sharp. While this is not an inexpensive lens, it is a great deal when compared to Canon's super telephoto lenses.

If you need/want an f/2.8 aperture in a zoom lens longer than 200mm, the Sigma 120-300mm f/2.8 DG OS HSM Sports Lens is your only current option aside from this lens's predecessor, the Sigma 120-300mm f/2.8 EX DG OS HSM Lens and that lens's predecessor, the Sigma 120-300mm f/2.8 DG HSM Lens. Yes, the green giant Sigma 200-500mm f/2.8 EX DG IF Power Zoom Lens exists, but this lens is merely a dream to most of our wallets – and handholding it is a dream to most of our biceps.

I know, these three 120-300mm lens names are confusing to me also. Hang with me on this: The "EX" non-"OS" version came first. The "EX OS" version came next. And the non-"EX" with-"OS" version, the first "Sports" ("S") lens available in the new-at-this-time Sigma Global Vision lineup, came next. This is the lens I am reviewing here and this is the one you want.

I'll get to the differences between this lens and the predecessor later in the review, but with your permission, I'm going to borrow some of the similarities in this review. And first, I'm going to borrow the 120-300mm application I encountered just after receiving the EX OS lens. It is completely applicable to the OS "S" lens as well and shows the benefit of having a focal length range in a sports lens.

I usually have a new lens run through my standardized testing procedures before using it for a real world application of any importance, but ... the Sigma 120-300 OS arrived just before I was going out the door to shoot a track and field meet. I had been shooting these meets with only the Canon EF 400mm f/2.8 L IS II USM Lens, but ... I couldn't resist taking this lens instead.

An f/2.8 max aperture combined with telephoto focal lengths begs to be used for sports and other low light action. The zoom range adds a great dimension the 300mm or 400mm fixed lenses do not have available to them. In-camera reviewing during the meet showed that the 120-300 OS was performing quite well.

The meet ended and I was packing up when one a member of the girls' team asked if I would take a picture of "us" with their coach. The local girls had just won the meet - against a team that went undefeated for 147 meets. The opposing team had not lost a meet for nearly 18 years - before any of the current team members had been born.

I understood the importance of this win to them, said "Sure" and got the camera back out. My initial understanding of "us" was a small group of girls (a handful of friends). As I walked toward where their coach was, I realized that an entire track and field team photo was being arranged for. On the track, right in front of the grandstands.

I stood on the absolute top seat in the stands and, at 120mm, after having the team move closer together, was able to get everyone in the frame. If I had only the 400mm lens with me on this day, the team would have had to be on the other side of the track to fit in the frame – and there would have been no hope for anyone hearing my instructions. Basically, if I didn't pick the Sigma 120-300mm f/2.8 DG OS HSM Sports Lens to shoot with on that day, there would have been no team photo better than what my smart phone was capable of to capture the historic event as a team. Or, I would have had one nasty 400mm panorama to stitch together. Fixing blinking eyes and turned heads would have been another level of complexity in that case.

The sun had set by the time the team photo was being shot. This eliminated any harsh shadows to contend with, but made the handheld exposure more challenging. Fortunately, I was able to take advantage of the Sigma 120-300's OS to keep my ISO settings low and obtain a sharp handheld image. I kept the shutter speed just fast enough to stop the excited subjects' motion.

Again, that story was from the arrival of this lens's predecessor, but the new model is at least as capable handling that situation. Carrying a second and third lens is a common solution to the lack of zoom range problem, but if fast lens changes are needed, a second and/or third body must also be carried. And switching cameras is still not as fast as zooming out with the 120-300.

As I have said several times before, taking full advantage of this added zoom range benefit requires another level of skill when shooting fast action. Not only do you need to track the subject with the proper focus point(s) locked onto the subject while keeping the camera level – as with a fixed focal length/prime lens, but you also must concern yourself with rotating the zoom ring at the same time – which can counter the effort to keep the camera level. This is no different with this Sigma zoom than from any other zoom lens, but many of us are using long primes for sports action. The limitations of a prime lens make them easier to use. But, all else equal, a zoom lens will deliver significantly more and better-framed images.

Click on the image below to see a focal length and aperture comparison created using the 120-300mm EX OS and a full frame Canon EOS 5D Mark III DSLR. Long focal length f/2.8 lenses can create a great background blur and great separation of the subject from that background. The daisy examples shown in the comparison were taken at a near-minimum focus distance.

As I mentioned, the wide-as-it-gets-in-a-zoom-lens f/2.8 aperture begs to stop action - especially in low light. Add the telephoto focal lengths mean that sports are a primary target for the 120-300 OS. Another popular subject for this lens, especially with APS-C (1.6x) bodies, is wildlife.

The 120-300mm focal length range also makes this lens a capable indoor event and portrait lens, but the weight of this lens will challenge significant handholding durations. Most are going to be happier using this lens mounted to a monopod or tripod when shooting events - and these supports can limit event and portrait shooting flexibility.

If choosing to handhold this lens, OS (Optical Stabilization) comes to the rescue. According to Sigma, the Sigma 120-300mm f/2.8 DG OS HSM Sports Lens received the identical OS system performance as the 120-300 EX OS had – and Roger Cicala confirmed to me that the OS unit part number is identical between the two lenses. Thus, I did not retest this OS implementation's full capabilities, but of course used it during evaluation of this lens.

Optical stabilization was a major upgrade for the 120-300mm f/2.8 EX DG OS Lens over its non-OS predecessor. And OS remains a valuable lens feature to me. The 120-300's OS is well behaved (viewfinder image remains steady during OS startup) and features mode 1 (normal) and mode 2 (panning) options. With Sigma Dock compatibility, this lens's OS can be further configured to one of three settings described by Sigma as:

Dynamic View Mode – This mode offers a recognizable OS effect to the image in the viewfinder. This helps to ensure the composition of images quickly.

Standard – This is the default setting. The OS effect is well-balanced and suitable for various scenes.

Moderate View Mode – This mode offers an excellent compensation of camera shake, and achieves smooth transition of the image in the viewfinder. The composition of the image remains natural even when the angle of view keeps changing.

Sigma claims 4 stops of handholdability from this implementation of OS. What I know from the 120-300mm "EX" OS review is:

At 120mm, I can get good handheld results down to 1/13 and 1/10 second exposures - representing approximately 3.5 stops of improvement for me. A few sharp 120mm images were captured at exposures as long as 1/6 second. A situation that requires a 1/6 second exposure duration at f/2.8 is quite dark.

Longer focal length lenses typically require shorter exposures/faster shutter speeds to deliver sharp handheld results than their wider angle counterparts do. The narrower angle of view means that subject details will cross more sensor pixels with the same amount of movement as when using a wider angle lens. At 300mm, the 120-300 gives me good handheld results down to 1/25 and 1/20 seconds with a few sharp images being made at exposures as long as 1/13 second. This is about a 3.5 stop or slightly better improvement over non-OS results.

Following is a 300mm 1/13 second exposure comparison.

Load Comparison Images

There is no question that this lens can be handheld and that OS aids in doing so – but such use will be avoided most of the time by all but the strongest photographers.

High end zoom lenses do not typically perform as well optically as high end prime lenses – such as the competing Canon 300mm f/2.8 L IS II Lens. The big question is usually "How big is the difference?" With the 120-300 "EX OS", there was a noticeable difference in f/2.8 image quality. With the 120-300 OS "S", that difference has been significantly reduced.

Roger, after tearing down both OS versions of the 120-300, said it appeared that elements in these lenses could be interchanged. The optical design seems unchanged.

Regardless of the reason, test results show that the OS "S" lens is a significant upgrade optically.

The Sigma 120-300mm f/2.8 DG OS HSM Sports Lens is sharp throughout the entire focal length range and across the entire 35mm frame with a wide open aperture. Stopping down 1 stop to f/4 slightly sharpens the full frame corners at 120mm and the center of the frame at 300mm. Overall, the improvement in image sharpness seen at f/4 is not significant and stopping down is not necessary for excellent image sharpness from this lens. You buy a lens like this to use at f/2.8 and this lens gives you what you pay for.

The much more expensive Canon EF 300mm f/2.8 L IS II Lens still compares favorably to the Sigma – at its only focal length. Many are not going to find the difference in image quality reflected in the difference in price.

The also-phenomenal Canon EF 70-200mm f/2.8 L IS II Lens' image quality is seriously challenged by the Sigma 120-300 S. The Sigma costs more in this case, but the 70-200 needs an extender to get out close to 300mm. And it becomes an f/4 lens in that case.

You also may think "280mm is not 300mm". This would be a good time to mention that specified focal lengths are not always exact - especially on zoom lenses. The Canon 300 f/2.8 IS II frames a just-under 4' wide target at 33.19' while the Sigma 120-300 OS S must be moved 2.24' closer (to 30.95') for the same target framing. The Canon 70-200 IS II frames the same target at 29.75' at 280mm (w/ 1.4x) - just 1.2' closer than the Sigma. Basically, the difference between the focal length of these lenses is not significant.

The 120-300 S has considerably sharper results than the 120-300 EX OS, which is considerably sharper than the original Sigma 120-300mm f/2.8 EX DG HSM Lens at wider apertures. Use the Image Quality tool link at the top of this review to see the differences between this lens and any other tested lenses at your choice of focal length and aperture.

More noticeably improved than image sharpness is vignetting when stopping down to f/4. But even this change is mild. Wide open full frame corner shading ranges from a mild 1.2 stops at 120mm up to a more-noticeable 2 stops at 300mm. Stopping down to f/5.6 completely eliminates corner shading save at the long end of the focal length range where f/11 completely removes this "defect". Whether corner shading is a negative or positive attribute is a matter of opinion and/or application, but I would rather add this effect in post processing than remove it if given the choice. Overall this lens shows little vignetting.

As usual, APS-C format sensors will not see much of a full frame lens's shading.

CA (Chromatic Aberration) is another image quality defect 120-300mm S lens owners will not need to worry about. Very little CA can be found in images from this lens.

Zoom lenses usually have barrel distortion at the wide end and pincushion distortion at the long end. This zoom lens, while not completely distortion free, definitely performs well in this regards. At 120mm, this lens is nearly distortion-free. A slight amount of pincushion distortion becomes apparent in the midrange and becomes mild at 300mm. Overall; this is a good showing from a zoom lens. The Canon 70-200 IS II Lens nearly mirrors the Sigma's performance. As expected from a prime, the Canon 300 f/2.8 IS II Lens is nearly distortion-free.

Being a relatively long focal length zoom with a high element count (23 lenses in 18 groups), the Sigma 120-300mm f/2.8 DG OS HSM Sports Lens comes out of the blocks disadvantaged in the flare category. However, it shows a marked improvement over the prior version of this lens by showing surprising little flaring even with the sun in the corner of the frame.

As shown in the sample photos shared above, the 120-300 OS can deliver a strong background blur and the quality of that blur (termed "bokeh") appears to be nice. With 9 aperture blades, this lens will create 18 point stars from OOF (Out of Focus) specular highlights when stopped down.

It doesn't matter how well a lens performs optically if the shot is out of focus. The Sigma 120-300mm f/2.8 DG OS HSM Sports Lens features Sigma's best-available-at-review-time HSM-driven AF system. HSM means Hypersonic Motor. Only a light "shhh" followed by some clicking sounds are heard inside the lens during AF. Focus speed is only acceptable (not that fast), especially with the cause of the clicking sounds at the end of focusing – focus correction that typically follows initial focus acquisition with this lens.

That is, unless the "Motor's drive speed priority" setting is programmed into and selected with one of the Custom Switch settings using Sigma's USB dock.

With that setting in place, this lens quickly acquires initial focus, though the extra/final AF corrections typically follow. Final focus adjustments keep this lens out of the best-available category in this regard, but my success rate with this lens has been quite good.

My AF accuracy experience with the 120-300 EX non-OS lens was not good. The 120-300 EX OS lens performed much better and the 120-300 OS "S" also performs quite well.

After calibration (correcting a slight but consistent backfocus), One Shot AF is no problem. In challenging AI Servo focusing situations, this lens has also proven capable. With well over 1,000 shots of galloping horses evaluated, I would not hesitate to use this lens for professional needs. Focus accuracy is good.

I asked Sigma why the faster AF speed was not selected by default. Their response indicated that the faster setting comes with a "slight risk of decrease in accuracy". The slower "Focus accuracy-priority" speed setting yields a higher accuracy rate while the "Standard" speed is a better general purpose setting. I'm led to believe that the slower speed setting may be a better choice in low light.

What I know is that I had a hard time telling the difference in accuracy when shooting the horses and that initial focus acquisition was much better with the high speed setting. The Sigma Dock is worth its price for this feature alone. Lighting conditions for these tests ranged from lightly cloudy to full sun in both front and back-lit positions.

I did not have focus calibration issues with this lens, but if you encounter such with your lens and camera combo, the dock can be used to correct this problem. With dock compatibility, consistent front or back focus issues can be corrected in the lens at 4 focus distances for 4 focal lengths.

The Sigma 120-300 OS focuses internally and FTM (Full Time Manual) focusing is available. New with the 120-300 OS "S" is a focus range limit switch. The dock can also be used to create your own focus limit ranges for especially fast focus acquisition in special situations. The front element does not rotate with focusing.

This lens is not parfocal. This means that focus should be reacquired after a focal length change. The difference in the necessary focus distance change needed with a focal length change is not big at longer distances, but much more dramatic at short focus distances.

The Sigma 120-300mm f/2.8 DG OS HSM Sports lens's focus ring is nicely-sized, smooth and well-damped with just the right amount of torque required to affect change. Videographers will be happy with that fact and also with the lack of focus breathing this lens shows. Subjects remain essentially the same size as they go in and out of focus. As expected from a quality lens, the image remains stable during manual focusing.

The 120-300mm EX OS did not win any medals for its MFD (Minimum Focus Distance) or MM (Maximum Magnification) values and the 120-300 OS "S" matches this spec. The Sigma is not alone as most lenses in this class have low MM specs. The 300mm daisy samples shown above were shot at near-MFD for this lens.

Model	Min Focus Distance "(mm)		Max Magnification
Canon EF 70-200mm f/2.8 L IS II USM Lens	47.2	(1200)	0.21x
Canon EF 100-400mm f/4.5-5.6 L IS USM Lens	70.9	(1800)	0.20x
Sigma 120-300mm f/2.8 DG OS HSM Lens	59.1	(1500)	0.12x
Sigma 120-300mm f/2.8 EX DG OS HSM Lens	59.1	(1500)	0.12x
Canon EF 200-400mm f/4 L IS USM 1.4x	78.7	(2000)	0.15, 0.21x
Canon EF 200mm f/2.0 L IS USM Lens	74.8	(1900)	0.12x
Canon EF 300mm f/4.0 L IS USM Lens	59.1	(1500)	0.24x
Canon EF 300mm f/2.8 L IS II USM Lens	78.7	(2000)	0.18x
Canon EF 300mm f/2.8 L IS USM Lens	98.4	(2500)	0.13x
Canon EF 400mm f/5.6 L USM Lens	137.8	(3500)	0.12x
Canon EF 400mm f/4.0 DO IS USM Lens	137.8	(3500)	0.12x
Canon EF 400mm f/2.8 L IS II USM Lens	106.3	(2700)	0.17x
Canon EF 400mm f/2.8 L IS USM Lens	118.1	(3000)	0.15x
Canon EF 500mm f/4.0 L IS II USM Lens	145.7	(3700)	0.15x
Canon EF 500mm f/4.0 L IS USM Lens	177.2	(4500)	0.12x
Canon EF 600mm f/4.0 L IS II USM Lens	177.2	(4500)	0.15x
Canon EF 600mm f/4.0 L IS USM Lens	216.5	(5500)	0.12x
Canon EF 800mm f/5.6 L IS USM Lens	236.2	(6000)	0.14x

Interesting is that the actual tested MFD for this lens ranges from 50.12" to 89.65" (1273mm to 2277mm). Those numbers correspond to 120mm through 300mm. The MM remains similar at 120mm as it is at 300mm.

As usual, Extension Tubes can improve these numbers - but not dramatically so.

Mounting a tele converter behind the Sigma 120-300 OS will make a much bigger difference in the MM values. The Sigma 120-300mm f/2.8 DG OS HSM Sports Lens is compatible with the Sigma 1.4x EX DG Tele Converter and Sigma 2x EX DG Tele Converter which result in a 1.4x and 2x increase in both focal length range and MM values. MFD remains the same - and OS continues to work.

With a 1.4x tele converter mounted, this lens becomes a 168-420mm f/4 OS Lens. With a 2x tele converter mounted, this lens becomes a 240-600mm f/5.6 OS Lens. Those are attractive numbers.

Unfortunately, there is a penalty to be paid when using a tele converter. As is often the case, this lens's image quality takes a hit with the tele converters in place.

The 1.4x noticeably reduces wide open image sharpness and noticeably increases CA. The 2x degrades sharpness even more, but CA does not take an additional hit. F/8 or f/11 produces the best results with this combination. By adding some barrel distortion, the 2x improves overall distortion. The image quality and distortion tools will show this clearly (use the links at the top of this review).

Load Comparison Images

The Sigma 120-300mm f/2.8 DG OS HSM Sports Lens is a well-constructed, pro-grade lens with new-for-this-model weather sealing. Sigma uses new Thermally Stable Composite (TSC) materials in this lens. TSC combines the characteristics of metal and polycarbonate and has the thermal expansion/contraction properties of aluminum. "Since thermal shrinkage is low, [TSC] has a high affinity to metal parts ..." and permits size reduction in other mechanical parts including the zoom ring. TSC also has a considerably higher elasticity compared to Sigma's other products.

The 120-300 "S" feels solid with this feeling being aided by the substantial weight. There is no play in any parts. This lens looks at least as good as it functions. And it feels nice in one's hands.

This is a fixed-physical-length lens - it does not extend with focal length change (a great feature). As with the focus ring, the Sigma 120-300 OS' zoom ring is nicely-sized, is smooth over the entire range and is well-damped with just the right amount of pressure required to affect change. It rotates in the standard Canon direction – opposite of Nikon's standard zoom ring rotation direction. I generally prefer the zoom ring to be located behind the focus ring, but in this case, the forward zoom ring position provides a good balance point for the lens. I would still prefer a forward-positioned focus ring – or at least some non-rotating lens barrel rear of the zoom ring to rest my hand on and allow fingertip rotation of the zoom ring.

Two of the four above-shown switches are new. I mentioned that this lens received a focus limiter – one switch is for that function. The other new switch I have also mentioned before – the Custom switch. This lens is compatible with Sigma's USB dock and the Sigma Dock review is a must-read for those considering the purchase of this lens. In short, the dock allows Custom switch 1 and 2 to be programmed to your specific needs including AF speed, focus distance limitation and OS settings. These settings are immediately available at the throw of a switch. Setting Custom switch 1 to "Motor's drive speed priority" was the first adjustment I made and that setting has become a strong preference for me.

More options mean more control. More options also mean more opportunities to get settings wrong – including accidentally wrong. Spend time learning your gear and check all settings before you shoot. If you would rather not have the options, simply use the default switch settings (but still check to insure that no switches are accidentally changed).

The tripod ring is included and is removable. Removal requires un-mounting the lens from the camera, but no hinge is needed on the ring, allowing a cleaner clamp-style design. To remove, simply loosen the large ring thumbscrew and rotate it to the remove mark. Then slide it off (with no camera mounted). This is a newly-designed, large tripod ring that, weighing more than twice the weight of the old one, is solid and rather wide.

I find this lens uncomfortable to carry by the tripod ring for long periods of time because the ring foot width spans more than my size-medium hand's second and third finger sections – digging into my less-padded finger joints. This design will not allow easy foot replacement either, though an entire aftermarket tripod ring could be developed.

With no weight on it, this tripod ring is smooth. Add weight and it is far less well-behaved. Expect binding while rotating the lens. No detents are provided at 90 degree rotation settings (though marks are available on the lens), but the binding will give you stops at random rotational settings.

Much improved is the tripod ring foot's depth. I received bruises from the prior model 120-300's raised switch panel hitting my fingers due to lack of clearance. That problem is gone.

With three 3/8" screw inserts (upgraded from a somewhat inadequate single insert) on the tripod foot, this lens is ready for the largest and most-secured lens plates. Or, if thread-attaching directly to a tripod or monopod, you have three positions to select from.

You can see the tripod clamping mechanism in the above photo. Overall, this is a nice design with a quality feel to it. Note that when clamped tight, the joint is offset slightly and becomes slightly sharp against the gripping hand.

Also more than doubling in weight is the 120-300's new lens hood. The new hood is substantial, utilizing a quality metal in a bayonet-mount and thumbscrew-locking design with a molded-in ridged-grooved interior and rubberized surface at the end of the hood. It looks and feels great. It provides solid good protection for the front lens element.

The round lens hood nicely supports the camera and lens sitting upright on it. This is nice for relieving your arms while shooting handheld. I have more confidence sitting this lens down on the hood than I did with the previous model's plastic hood. The hood is adequately sized for installing and removing the traditional style center-and-side-pinch plastic lens cap with the hood in place. You will likely want to remove the hood when adjusting a circular polarizer filter.

Unlike Canon's big guns that accept drop-in filters, the Sigma 120-300 OS accepts front filters. The 105mm filters are huge and quality versions are going to set you back at checkout, but having the option is a positive feature. The Canon drop-in filters are at least as expensive. I mentioned earlier in this review that the front element does not rotate – this is important for CP filter use.

The Sigma 120-300 OS Lens ships with a zippered padded nylon case with a shoulder strap. While nice, the case would be much more functional with a few additional inches of length - enough to allow a mounted DSLR to fit.

A lens neck strap is also included:

This is a substantial lens. Let's compare using a table of telephoto lens manufacturer weight specifications.

Model	Weight oz(g)		Dimensions w/o Hood "(mm)		Filter	Year
Canon EF 70-200mm f/2.8 L IS II USM Lens	3.30 lbs	(1490)	3.5 x 7.8	(88.8 x 199)	77mm	2010
Sigma 120-300mm f/2.8 DG OS HSM	7.50 lbs	(3390)	4.9 x 11.5	(124.4 x 291)	105mm	2013
Sigma 120-300mm f/2.8 EX DG OS HSM Lens	6.50 lbs	(2950)	5.0 x 11.4	(127 x 289.6)	105mm	2012
Sigma 120-300mm f/2.8 EX DG HSM Lens	5.75 lbs	(2600)	4.4 x 10.6	(113 x 269)	105mm
Canon EF 200-400mm f/4 L IS USM 1.4x	8.00 lbs	(3620)	5.0 x 14.4	(128 x 366)	DI 52mm	2013
Canon EF 200mm f/2.0 L IS USM Lens	5.56 lbs	(2520)	5.0 x 8.2	(128 x 208)	DI 52mm	2008
Canon EF 300mm f/4.0 L IS USM Lens	2.63 lbs	(1190)	3.5 x 8.7	(90 x 221)	77mm	1997
Canon EF 300mm f/2.8 L IS II USM Lens	5.19 lbs	(2350)	5.0 x 9.8	(128 x 248)	DI 52mm	2011
Canon EF 300mm f/2.8 L IS USM Lens	5.63 lbs	(2550)	5.0 x 9.9	(128 x 252)	DI 52mm	1999
Canon EF 100-400mm f/4.5-5.6 L IS USM	3.04 lbs	(1380)	3.6 x 7.4	(92 x 189)	77mm	1998
Canon EF 400mm f/5.6 L USM Lens	2.76 lbs	(1250)	3.5 x 10.1	(90 x 257)	77mm	1993
Canon EF 400mm f/4.0 DO IS USM Lens	4.28 lbs	(1940)	5.0 x 9.1	(128 x 232)	DI 52mm	2001
Canon EF 400mm f/2.8 L IS II USM Lens	8.49 lbs	(3850)	6.4 x 13.5	(163 x 343)	DI 52mm	2011
Canon EF 400mm f/2.8 L IS USM Lens	11.85 lbs	(5370)	6.4 x 13.7	(163 x 349)	DI 52mm	1999
Canon EF 500mm f/4.0 L IS II USM Lens	7.04 lbs	(3190)	5.7 x 15.1	(146 x 383)	DI 52mm	2011
Canon EF 500mm f/4.0 L IS USM Lens	8.54 lbs	(3870)	5.7 x 15.2	(146 x 387)	DI 52mm	1999
Canon EF 600mm f/4.0 L IS II USM Lens	8.65 lbs	(3920)	6.6 x 17.6	(168 x 448)	DI 52mm	2011
Canon EF 600mm f/4.0 L IS USM Lens	11.83 lbs	(5360)	6.6 x 18.0	(168 x 456)	DI 52mm	1999
Canon EF 800mm f/5.6 L IS USM Lens	9.86 lbs	(4470)	6.4 x 18.1	(163 x 461)	DI 52mm	2008

For many more comparisons, review the complete Sigma 120-300mm f/2.8 DG OS HSM Sports Lens Specifications using the site's Lens Spec tool.

The EX DG OS lens gained 12.3 oz (350g) in weight and .55 x .81" (14 x 20mm) in size over the prior non-OS version of this lens. The 120-300mm OS "S" lens gained another pound (440g) with much of that weight gain in the tripod ring and hood. Fully loaded and ready for use, it is now a noticeable 2.3 lbs (1040g) heavier than Canon's competing 300mm f/2.8 prime lens, the Canon EF 300mm f/2.8 L IS II USM Lens. The Sigma of course retains the strong zoom range advantage over that lens. Carrying a second lens will quickly eat up that weight difference.

Tripod mounting a lens of this size requires a solid tripod and strong tripod head. The Wimberley Tripod Head II, a gimbal-style head, is my preference for lenses of this weight.

Here is a pictorial size comparison of the Sigma 120-300 OS, 120-300 EX OS and some of Canon's big white lenses:

Positioned above from left to right are the following lenses:

Canon EF 200mm f/2.0 L IS USM Lens
Canon EF 300mm f/2.8 L IS II USM Lens
Sigma 120-300mm f/2.8 EX DG OS HSM Lens
Sigma 120-300mm f/2.8 DG OS HSM Sports Lens
Canon EF 200-400mm f/4 L IS USM 1.4x

The same lenses are shown below with their lens hoods in place.

The 300 is smaller and the 200-400 is larger. I have not talked much about the 200-400 L in this review. While it is Canon's only big zoom lens, I don't see this lens and the Sigma competing too often. Those who want focal length will want the Canon (if they can afford it) and those needing f/2.8 and wider focal lengths will want the Sigma (or another option).

Here is a closer look at the old (top) and new (bottom) Sigma OS lenses:

These lenses look more similar than different. You will see some more-glossy-finished areas of the newer lens, a bumped-out section of the zoom ring, slightly different contouring of the lens and hood along with the already-noted tripod ring changes. The gold ring is gone and the chrome "S" badge is, of course, new. I asked Sigma for a "detailed" list of changes in the new lens and they honored my request by even pointing out the new badge in their response. :) It looks classy.

Here is a more-complete list of changes/updates in this lens:

• USB Dock Compatibility
  • Firmware is updatable
  • Detailed AF calibration is possible
  • Custom switch with 2 OS, 3 AF speed and AF focus limiter programmable settings
• Substantially upgraded lens hood
• New barrel design with style improvements
• Manufacturing year stamped at lens base
• “S” Sport silver tab label (the gold ring is gone)
• Updated cam for smoother focusing
• New switches
• All lenses tested using Sigma's new MTF A1 testing system
• Use of Thermally Stable Composite (TSC) material in lens barrel
  • High affinity to metal parts
  • 25% greater elasticity compared to polycarbonate
  • Increased overall durability
  • More resistant to extreme weather
  • Allows reduction in size and weight
• Three screw inserts in the tripod foot
• Dust and Splash proof design
• Sturdier and stronger tripod collar
• Addition of focus limiter
• Updated AF algorithm for smoother AF
• $1,000.00 USD higher price at review time

Is this lens worth $1,000.00 more than the previous version? To me, definitely. The image quality improvement alone is worth that to me. I'm sure that not all will agree, but ... hopefully you now have enough information to make that decision for yourself.

The Sigma 120-300mm f/2.8 DG OS HSM Sports Lens is available in Canon (reviewed), Nikon, and Sigma mounts. My standard disclaimer: There are some potential issues with third party lenses. Since Sigma reverse engineers (vs. licenses) manufacturer AF routines, there is always the possibility that a DSLR body might not support a (likely older) third party lens. Sometimes a lens can be made compatible by the manufacturer, sometimes not. There is also the risk of a problem that results in the lens and body manufacturers directing blame at each other. Sigma USA's 4-year warranty is far superior to Canon's standard 1 year warranty (Sigma's international warranty is also 1 year). Sigma USB Dock compatibility with the ability to update firmware is added insurance against such a future problem.

I've been comparing the Sigma 120-300 OS with the Canon 70-200 f/2.8 L IS II USM Lens and the Canon EF 300mm f/2.8 L IS II USM Lens most directly throughout this review. These are Canon's most-similar models from a feature perspective. The two Canons cover much of the Sigma's overall focal length range – the pair leave a 201-299mm gap and pick up the 70-119mm range. They also share the f/2.8 max aperture and have image stabilization. The Sigma has the focal length range convenience advantage. The Canon 300 L II has the image quality advantage, though this is not huge. If forced to pick, I'd take the Canon AF systems.

I wouldn't have to be forced to pick the price. While the Canon 70-200 II is less expensive, you could buy the Sigma 120-300 OS Lens and a high end Canon DSLR camera for the price of one Canon 300 IS II. This fact will grab attention.

Based on what I was initially hearing and understanding about this lens, I figured I'd pick up a 120-300 "S", capture the standard image quality test results, use it a little bit, write a little bit and move it along. But, my plans changed – especially after I saw the image quality this lens delivered. Based on a more-than-expected amount of time with this lens, I'm quite pleased with to say that I really like what Sigma has done with this lens model.

It is hard not to like a great looking lens with a 120-300mm focal length range in a non-extending, solidly built body that also feels great – and delivers image quality that leaves most other zoom lenses wanting even at this lens's wide max f/2.8 aperture. I like the direction Sigma has been going with their recent lenses and I think they have another hit with the Sigma 120-300mm f/2.8 DG OS HSM Sports Lens.