Yeah, I actually researched before I bought my lens, crazy hey. I couldn't find my original source that had a direct chart comparison of all of the four mark I 70-200's but I think this will make my point just fine.
Even if the price and weight were the same, the $1,700, three-pound f/2.8 IS lens doesn't offer me that much more. If you look at the falloff of the 70-200mm f/2.8 L IS in my review, f/2.8 has far more falloff than this f/4 at f/4, so the one stop for which you're paying dearly isn't really f/2.8 except in the center of the image. Also I need a second hand to zoom the Canon 70-200mm f/2.8 L IS, instead of a flick of a fingertip with this f/4 L IS. The f/2.8 has more flare.
-Ken Rockwell. www.kenrockwell.com
That rules out the 2.8 IS for you!
Verdict
Every now and then EOS, the goddess of mercy, seems to speak to the Canon lens designers and this time they listened carefully. The Canon EF 70-200mm f/4 USM L IS may well be the VERY BEST tele zoom on the market today - it is CERTAINLY THE BEST Canon zoom lens tested locally to date. The lens was capable to deliver a near-flawless performance is all categories. The resolution figures are stunning regardless of the setting. Distortions, vignetting and CAs are nothing to worry about. The build quality is excellent with the new sealing as a another highlight. On top of that the lens now features a image stabilizer with an efficiency equivalent to 4 f-stops (at cost of shutter speed).
- Photozone.de That proves my point completely..
Sharpness
My own sharpness comparison testing of the 70-200 F4.0 IS and 70-200 F2.8 non-IS lens models only confirmed what Canon’s MTF charts predicted. I used both real world photos and shots of newspaper classified ads taped to a wall. One sheet was placed at the center and another was placed near the corner of the frame. While this is not quantifiable scientific testing, it was well enough controlled that I am confident that the comparisons are accurate. This testing showed the F4.0 IS lens to have substantially greater contrast and sharpness than my F2.8 lens at the apertures I tested. In my tests at F4.0, the F4.0 IS lens was visibly sharper across the entire image, including in the center. By F8 I could not tell any difference in the center sharpness, but the F4.0 IS lens was still visibly sharper at any point further than half way to the frame edge from the center, in the long dimension of the frame. In other words, in terms of a 24x36 mm frame, everything more than 9mm from the center was visibly sharper with the 70-200 F4.0 IS lens. The difference in edge contrast and sharpness is so substantial that in A/B comparisons I could tell which lens was used for any given shot without referring to my notes. The sharpness difference is somewhat less pronounced at smaller apertures, but it is still quite apparent even at F11 and F16.
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That’s not all there is to say about the outstanding sharpness and contrast of the Canon 70-200 F4.0 IS L lens. I also compared it at 70mm to my 24-70 F2.8 L lens, and at 90mm to my 90mm F2.8 Tilt/Shift lens (with no tilt or shift applied). The results show the EF 70-200 F4.0 IS L zoom lens to have somewhat better sharpness and contrast than the EF 24-70 F2.8 L lens, and nearly identical sharpness and contrast when compared to the 90mm F2.8 TS-E lens, which is remarkably sharp.
There's more evidence just to throw in there that the IS doesn't affect IQ.
Enjoy the knowledge bud.
http://www.dmcphoto.com/Articles/Canon70-200F4ISL/index.html
