From Sigma 70-200 2.8 OS to Canon 70-200 2.8 Mark II

I Myself was in the same predicament you are in. I had the 70-200 F/4L and didn't REALLY want to spend the money but I did. I can say it is 100% worth the money and it's hardly come off my camera in most instances. It works incredibly well with a FF setup such like yourself. Don't skimp out on lens'. If you ever find yourself in a tough place, the value is kept for a LONG time.

I am still playing with a new Canon 70-200 IS II - and from what I've seen so far- a mixed bag. It IS a bit sharper wide open, and a bit heavier, and a bit more white.. technically, the white beast is physically larger and seems heavier- there are other subtle differences. It does seem that the Sigma is a little short in focal length, but that could be focus breathing ( ?? - maybe around 180mm instead of 200mm) If I am forced to sell one of them, depending upon how much money I need at the time, I'd probably sell the sigma. I never had any problems with focusing on the Sigma, other than it seeming a bit soft at 2.8- which goes away at about 3.2 ~3.5. If I was strapped for money, I'd take the Sigma any day of the week. I am talking about the 70-200 EX DG HSM OS.. However, if you have the money or can get it, and if you think you might want it- go for the Canon and be done.

Vignetting- seen more vignetting on the Sigma than the Canon as well- especially on the 5D III. The Sigma plays nicely with its 1.4x and 2.0x TC's. Surprisingly nicely. I should get the Canon extenders later this week. While the Sigma's focusing was never a problem, the Canon L's do seem snappier and a little crisper..

Additional notes: Going to the Sigma 70-200 from the 55-250 kit lens- that was a wow- an eyeopener on how much difference there was. If I was buying, for the first time, a quality 70-200, and thought I'd be reconsidering going with a Canon 70-200 f/2.8 IS II- then you are right- reconsider now before you buy- and buy once. . The reality is that most copies of the Sigma 70-200 OS are relatively sharp at f/3.2, while some are that way at f/2.8. That's one notch slower for shutter speed or one notch higher ISO wise ( 1/3rd stop). For most, that won't matter. And yes, I can fully understand those that like their Tamron 70-200 f/2.8.

One of the biggest issues I have with comparing the two- is - it's like comparing two different lenses rather than two similar lenses. Out of the gate, the Canon's AF seems to be more accurate- I haven't seen it miss in one-shot. Never noticed the issue with the Sigma- it's always been a little softer at 2.8- so I always stopped it down to 3.2 or 3.5 or 4.0. Now, let's say I am sitting and take a shot with both lenses at the same mm setting- same aperture, etc, the Canon's FOV is different- closer - significantly closer than the Sigma. So, when looking at details- not only does the Canon look bigger as far as details are concerned- so is the sharpness. But are we seeing the larger details as an improvement in detail ? IDK.

The weekend is coming, and hopefully, I will get out and get more experience with the two sets of lenses and maybe by then I will see the "difference", but so far- it's slightly better..

Having owned both, it's the mkII that takes the cake. I had the chance to own both side by side and used them on 5dmkII and the 1mkIII. While the sigma is 90% it's that 10% that wows me. I found that the sigma left me wanting more. I never felt like it stopped me from getting shots, but it did leave me second guessing and working a little harder. With that said, if you don't have the means, don't overlook what sigma brings. Just know that the MKII is better.
My pennies worth...

^^^ My thoughts on this- that second guessing- most of it came from this forum, for me. I'm not sure that the numbers should be 90% / 10% though.. If I'd have kept out of this forum, my bank account probably would have been happier.

jmcgee131 wrote in post #14471357
Having owned both, it's the mkII that takes the cake. I had the chance to own both side by side and used them on 5dmkII and the 1mkIII. While the sigma is 90% it's that 10% that wows me. I found that the sigma left me wanting more. I never felt like it stopped me from getting shots, but it did leave me second guessing and working a little harder. With that said, if you don't have the means, don't overlook what sigma brings. Just know that the MKII is better.
My pennies worth...

I feel similarly having owned all three Canon varieties and now owning the Sigma OS. Most noticably, the difference comes down to AF speed/accuracy rather than IQ, imo.