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Question: Canon 70-200 f/4, f/2.8. IS non-IS.. for sports Which would be best for shooting mostly sports? The f/4 IS or the f/2.8 IS?
Document: I previously owned the 70-200 f/4L non-IS. I still maintain that is one of the best values in the L series line of lenses. However after shooting motorcycles with a few lenses that had mode 2 IS I decided to sell my non-IS lens and get this f/4 IS lens. Why, hit rate, I love doing the slower shutter speed panning shots of the motorcycles at the race track.
Obviously this is slower than you'll likely need to go, but that's how good this IS is. It is among the best Canon offers.The other obvious choices for comparing this lens are the 70-200mmf/2.8 non-ISandf/2.8 ISversions. Without IS, the f/2.8 price is the same, yet even if you can afford the $2,500 version, this f/4 IS is still, in my opinion, the best choice.
Before purchased, I used the 70-200 2.8 IS and found it very heavy. I usually missed shots because I was not in position to take pictures. I also tried the 70-300 but found the focus too slow for sports.I since purchased the 70-200 4/IS and found it the best sports lens to have on my camera. This lens is light enough to shoot with one hand (with the IS on). On my 40D it reaches to 320.
The Sigma didnt have OS, but it was F/2.8 and $400 cheaper. The Canon F/2.8 IS didnt make the list because it was way over my budget. There were many reviews online that mentioned that f/4 IS is probably the best optically among all 4 Canon 70-200 lenses. However, F/2.8 was tempting on the sigma and the canon. After a long while, I finally made my choice: Canon 70-200 L IS.
there is absolutely nothing i would change. (except maybe the price. free would be nice.) the two biggest questions when trying to select a 70-200 canon lens are always "do i pay for IS?" and "do i get the f/2.8 or the f/4?". i can't answer that for you, but ask yourself these questions respectively:  do you always shoot in bright light with fast shutter speeds?
I finally pulled the trigger and purchased the 70-200 f/4 IS for my Canon 5D Mark II. I had been battling back and forth between the very expensive and very heavy 2.8 IS and wondered if I would regret getting the f/4. Prior to my purchase, I rented a 2.8 IS from Samy's Camera and had it for the weekend. I shot a great event.
Excellent contrast, color, and sharpness. The f/4L IS offers a much more pleasing bokeh than the non-IS version, which I've used, due to the newer shape and positioning of the blades. This lens is only second to the 70-200mm f/2.8L IS mkII, and it's not far behind. Given the price and weight difference between this lens and the mkII, I'd say this is definitely the way to go unless you're shooting indoor sports or need super-bokeh.
In the past I've always had under-performing zooms in this range, so when I switched to Canon I wanted a good sharp lens. I hike a lot, so the size and mass of this lens (vs. the 2.8) and the possibility of using it hand held were big selling points. I mostly shoot non-moving subjects, if you shoot sports or moving subjects you may have different needs.While I expected this lens to be good, the reality of the lens surpassed my expectations .
The moving versus non-moving distinction is so important that I actually ended up owning BOTH the f/2.8 IS and the f/4 IS. Why? Because the f/2.8 IS is the strongest contender for low-light event work out of the 70-200 line, yet offers the worst in image quality. The image quality difference between the f/4 and the f/2.8 is nothing short of  significant.
This lens provides image quality comparable to the best primes with image stabilization and the versatility of a zoom. That makes it a must have for a basic lens collection. I am shooting on a 1Ds III that tests every lens to the max and previously owned the non IS version of this lens. It was not as sharp as primes like the 135mm f.2 or the 85mm f1.8. My first priority is image quality so I basically stopped using the zoom and relied on the primes instead.
Answer: These are two wonderful lens. Both have their advantages and disadvantages.  Lets start with the f/4 IS.  You have great IS capable of shooting sharp images up to to four stops without a tripod.  However, you will not be able to stop the action in low light because of the F/4 aperture.  IS fixes the shakes from your hands, it has no effect of freezing action in low or dim light.  You could raise your ISO, but then you have to worry about noise.  The weight of the F/4 will be much more comfortable around your neck than the f/2.8 because it weighs almost half as much.  The price of the f/4 is another factor.  Its around $500.00 bucks cheaper.   The f/2.8 IS is a beast that will produce fantastic images but you are going to pay a price for it.  It's heavy and you need to have deep pockets.  On the other hand if sports is your thing and creating fantastic images with great bokeh than why not splurg and get what you really want.  Are you shooting indoor sports? You should probably consider the f/2.8.  Either way you are going to spend some money and you might as well get the one that is going to fit your needs.  To sum up if you are shooting indoor sports i would go with the 2.8.  If not the f/4 will not dissappoint you.