Excerpt: I use it for all types of wildlife, Flowers, air shows, fast sailboats etc. This is one amazing lens as long as you have enough light to satisfy that f/6.3. It has nice crisp focus and feels nice and tight around the barrel. The only drawback is it's 4lbs. weight but so is the rest of them around this size. Best advice is, shop around. It can vary in the hundreds in price between different sites.
Pros: Consistent Output, Easily Interchangeable, Fast / accurate auto-focus, Rugged, Strong Construction
Summary: Just got the beast. It is a nearly 2Kg lens, which means that shooting by hand is tiresome to say the least. If stabilized correctly, the quality of the pictures is excellent. I attached a pistol remote shutter release to the tripod strip, and handling got a lot easier. as far as the super telephoto lens are concerned, this one is extremely good value for money, since the quality is adequate, the price is ~ 1/3 of any other decent fixed F# lens, and the versatility of...
Excerpt: Wasn't sure exactly what this lens would be like when I ordered it. First thing you notice is that its huge and heavy (heavy usually = quality). When you attach the lens hoods this lens looks like a telescope. At 500mm I was thinking there would be no way I could hand hold it and get sharp photos, but wow was I wrong. Even fully extended to 500mm and shooting wide open my photos are crisp.
Pros: Fast / accurate auto-focus, OS, Range, Value
Excerpt: I use it for taking great photographs of birds and wildlife, especially in Costa Rica. It really brings the feathers and features into sharp focus with fine detail. I have successfully photographed birds flying with wings spread as well as tiny frogs. I use them on calendars to promote education about the environment. I appreciate being able to use it on close and distant objects since it has such a wide range.
Pros: Consistent Output, Durable, Easily Interchangeable, Rugged, Strong Construction
Summary: Yes, it's heavy. But if you are comfortable with a 70-200mm, you will instantly appreciate the extra "reach" on both ends. It's not THAT much heavier. While it excels in telephoto work, you can still dial it back and get a "normal" 50mm. Which means less missed shots because they are too close. On the far end, you can get those wildlife shots that need the full 500mm magnification (and probably at least a monopod to steady). And everythhing between.
Summary: Just received the lens and got to play with it. I think I died and went to heaven. Fast auto focus, crisp clear pictures whether at 50mm or 500mm. I can't wait to use it some more. It is a bit heavy but I was still able to hold it to take pictures without a tripod. I will most likely use a monopod if I am planning to shoot for a longer time. I gave up my Sony 400mm telephoto and will be using this on my Alpha 77.
Summary: I've owned this lens for 8 months now. Although, I'll rent the EX 70-200mm f2.8 IS II (unsurpassed image quality) when shooting professionally because of its low light capability, I won't even consider selling my Sigma 50-500mm f/4-6.3 EX DG APO HSM OS (affectionately called "Bigma") to offset the cost of buying the rental lens. With a 10X (ten times 50mm) focal length, this lens covers just about any well lighted shooting opportunities.