My new 'Cannon' is a Sigma

My Current Sideline Rig

I've been rocking the Canon 300mmF2.8L on the sidelines for several years now and it has served me well but I was always disappointed when the action came at me or when an spectacular catch happened just feet away from me, I'd end up missing an awesome shot because it was just too tight. I've tried using a second body with a shorter lens but it still wasn't quick or as spontaneous as I'd like. (and since I don't shoot for SI, I felt like a bit of a douche carrying two cameras around).
So this season I picked up the newly released Sigma 120-300mm F2.8 DG OS HSM. Yes, that's a fixed 2.8 aperture, image stabilized, tele to super-tele zoom! I admit, I had my doubts, I've been burned by the inferior image quality of 3rd party lenses before and vowed 'never-again'. I've also read enough reports of just how poor previous versions of this lens (I think this is the 3rd) was that I never really considered it. But in 2013, Sigma has stepped up thier game and started putting out some really fine lenses. Their new 35mm F1.4 prime is truly a 'best in class' lens and has got owners of Canon and Nikon 35s asking themselves why they spent more and got less. So when I read that this lens would be built to the same standards, my curiosity was piqued.
So how did it perform? At first, poorly. I shot two games with it and had a really low 'keeper' rate due to out of focus shots.  But after doing a little research, I found that Sigma programs the AF system to prioritize focus accuracy over focus speed. So I used the Sigma USB dock to setup a custom profile for the lens - (there are two custom profile slots that can store different AF speed profiles and AF Microadjustments which is Sigma's work around for the Camera manufacturers not including 3rd party lenses in their in-camera micro focus adjustments). I set mine up for the High Speed setting and went off and shot another game. Keeper rate was MUCH better, pretty close to on par with the ol' Canon 300. This really is a different lens in this mode. Why Sigma doesn't ship their 'Sports' lens with High Speed AF as default is a mystery, but they do.
Now with the focus issue out of the way I could do some comparisons.

Sharpness:
Very good - I only shoot this lens wide open and it does a good job. It's not quite as sharp as the Canon 300F2.8L but not much else is. I did find it sharper than the 300F4ISL that I used to own. One peculiar characteristic of this lens is that it doesn't seem as sharp on distant objects - don't know if this has to do with the resolving capability of the lens but I noticed that within 50 yards or so, subjects are tack sharp but as distance increases they tend to go soft - I never experienced this with the Canon.

Bokeh:
While I don't intend to use this as a portrait lens, good bokeh is important to get subject / background separation and here a think the Sigma is a bit better than the canon. Specular highlights with my canon were often harsh and had an almost crystallized look to them which could be distracting at times, not a problem with the Sigma, nice round soft orbs of light is all you get here.
Color and Contrast
Since I shoot mainly night games under crappy lights I really can't comment on this one other than under the same conditions I'm finding I'm doing a little more 'tweaking' in Lightroom with the Sigma so I'd take it that to mean the Canon is better (at least in this situation)
Flexibility
Obviously, the Sigma is the hands down winner here since the Canon can't zoom. It is just so great to be able to track a subject coming at you and adjust framing at the same time. The 120mm is by no means wide but on a football field, it's enough to capture the entire coaches huddle or snap sideline portraits without having to back way the hell up. It should be noted that the lens is not a parfocal design so focus changes slightly as you zoom, but I don't think that matters much with AF.

Stretching for the Goal line
Sigma 120-300 @150mm

Here's a shot of a QB keeper play that went to my side, I was able to zoom out and put a little context to his outstretched ball by capturing some of the goal line. With the Canon this would have been 3/4 shot and while it might have been a nice tight shot of his facial expression, I like having the choice to frame the way I want.




In the end, do I think the Sigma is a keeper? Well, all I have to say is there's a big white lens is on craigslist right now...