I know, if you're thinking of splashing out $1200 for a lens, you should know damn well what you intend to use it for. However, I'm very confused between two version of Canon's EF 70-200 L lenses that are around the same price - the 70-200 F4L IS and the 70-200 F2.8L (non IS). I intend to shoot animals, vehicles, aircraft and the odd portrait. Basically a lot of my usual stuff but tighter framing on camera so that I don't have to crop in post. The F4L looks good because it has IS and reviews say it's light and thanks to the IS, is very handholdable at slow shutter speeds. The IS is 3-4 stops. The F2.8L has a wider aperture, but in terms of light is only one stop faster than the F4L and the weight/size make it inherently less handholdable, from what I hear. So which one makes more sense? I'm tired of vacillating between the two and I would just like some help making up my mind.
TBH, for animals (Wildlife?), vehicles and aircraft the 100-400 would be a better bet than any of the 70-200 series lenses. It is a stop slower than the 70-200/4 IS and the IS isn't as good BUT the range is far more suitable for that subject matter. Granted, it is a bit more expensive. The 70-200/4 IS is one of Canon's best zoom lenses ever in terms of IQ, and its relatively small weight and size makes for a good light weight alternative to the focal range. The f/2.8 version is known to be less sharp wide open (with better bokeh) BUT nearly indistinguishable in terms of IQ compared to the f/4 IS stopped down to f/4 with better vignetting control. If you need f/2.8 get the 2.8, if not go with the f/4 IS. And FWIW, a stop can make a huge difference and keep in mind IS does NOT stop motion, so while it does play a role it's not so large with moving subjects.
The 100-400 is way out of my price range. What I would really like to know is whether the 70-200 F4 has decent background blur at MFD at 70mm. If it's capable of isolating a foreground subject (or blurring the foreground for a background subject) then I'll go with that, because I rarely use tripods and I need a long-ish lens that's handholdable.
I've got a 70-200 F2.8L and a 70-200 F4L (both without IS). Isolating subjects at 70mm F4 is easy enough and both produce nice bokeh. The F4L is sharper wide open than the F2.8L, but once you stop the latter down to F4, it's pretty similar. The F2.8L benefits from a brighter viewfinder, which makes focusing easier for me, but I often find myself reaching for a monopod in low light, but if you've got good high ISO performance you can get away with hand-holding and it performs fine as long as you've got a 1/200th shutter speed at 200mm. I've not used a 70-200 F4L IS, but it's widely regarded as one of Canon's best zoom lenses. It's razor sharp and is pretty light (not much heavier than the F4L non-IS). IS is well implemented and will give you four stops, but it doesn't freeze motion so in some respects the F2.8L will be more useful. I mainly use my camera on a tripod, so the F2.8L is fine for my purposes - I don't find myself needing IS often enough to justify the price hike, even though it'd be nice to have for those occasions where I could benefit from it. Ultimately, you've got to decide whether IS will be useful to you or not and by the sounds of it, it will. You don't have anything to worry about in terms of IQ on the F4L IS, as it's one of Canon's sharpest-ever zooms.
Roger that. Thank you both, I think I'll get the F4L IS. And I just noticed it shares filter size with my Tamron, so that' a bonus
Depending on subject to lens and subject to background distance, the f/2.8 version will generally get you better bokeh/BG blur, BUT the f/4 version is capable as well. IMO the f/2.8 versions of the 70-200 are handholdable, but ymmv. In your case the f/4IS is probably the better bet, but for portraits and action I'd rather have the f/2.8 version for the extra stop.
