Excerpt: Picture quality with a 70-200 is much better than the 18-135 kit lens which came with my 70D. The disadvantages are the length and weight of the lens. Also occasionally the auto focus feels a bit slower than the 18-135. That being said, considering the alternatives, the 70-200 F4 IS lens is a great product with reasonable price and I strongly recommend it.
Pros: Consistent Output, Durable, Fast / accurate auto-focus, Nice Bokeh, Strong Construction
Excerpt: I have used this lens for a few days now. Shot a bicycle event in very harsh sunlight, sunset sailboat races and twilight conditions . Surprising quality at such light weight. Very sharp at all apertures. Great contrast and color. I didn't have a lens hood on in some backlit and sidelit situations and had minimal lens flare. I used auto focus on tracking mode for a while and it worked well.
Pros: Fast / accurate auto-focus, Good Color Contrast, Lightweight, Nice Bokeh, Nice Feel To Focus-zoom, Very Sharp
Excerpt: First the good news: this is an excellent, sharp, lightweight lens. I chose to add it to fill the gap between the 24-105mm and my prime 300mm. It is a good "street" lens on my 5d Mk III for grabbing detail shots and close-ups without the weight of its big brother, the f2.8. The not-so-good news for me was that out of the box it frequently failed to autofocus correctly (or in some cases, at all).
Excerpt: This lens is great and brings my ability to capture tighter head shots to a whole new level. I highly recommend it. The only reason I gave it four stars instead of five is that it is limited in lens speed to the f4 aperture stop. However, I could not justify paying twice the money to gain one stop in lens speed. So this lens was my choice for economic reasons. Otherwise it is a great lens for the money.
Pros: Consistent Output, Durable, Lightweight, Nice Bokeh, Rugged, Strong Construction
Excerpt: This lens replaces my Canon 70-300 mm f/4-5.6 IS and is much sharper at longer focal lengths. In fact sharper with 200 mm cropped to equal image size of 300 mm than the old lens. Which is what I wanted. Functions extremely well with control setting on side easy to use. Seems like IS is better, too.
Pros: Does Not Extend, Fast / accurate auto-focus, Rugged, Sharp Images In Raw, Smooth Functioning, Strong Construction
Excerpt: Fantastic image quality. Needs good lighting, or a camera that works well at higher ISOs. Got good pics at a basketball game, but I pushed up the ISO so a bit grainy on my 400D. Fully zoomed, I can't hold it steady enough at anything less than 1/400 (the 400D has a 1.6x conversion factor); your milage may vary. The build quality is of course excellent, and the weight never bothers me.
Excerpt: This lens is incredible in every way - super sharp, great DOF, and much smaller and lighter than its f2.8 counterparts. However, in the end it could not compete with the speed and new optics of the f2.8 ver2, so I returned it and made the upgrade. But for the money and if you're not planning to show in any low light, this lens is a great value and makes beautiful images.