Summary: Extremely well built. Weatherproof. Excellent image quality. If there is a weak point, it would be focus speed. If Olympus would only come up with a camera that is worthy of their optical achievements...
Excerpt: This lens is pricey, but less than the comparable Nikon 200-400; the same for its size and weight. But that's to be expected of a lens of this quality. I have only used it once since buying it, shooting egrets, herons, and osprey...I added a 1.4x extender and still shot at f/4. I hooked it up to my new EM-5 via the M4/3 adapter, and used it with a Wimberly sidekick. The sharpness is superb...I look forward to many hours of quality shooting.
Pros: Consistent Output, Durable, Fast / accurate auto-focus, Rugged, Strong Construction
Excerpt: I use this Super Telephoto mostly for sports such as soccer, baseball, football, swimming, and even volleyball. It has the perfect telephoto range for capturing action fairly close and sufficient zoom range to grab shots out on the field and it works great with the EC-14 1.4X Teleconverter. It is razor sharp if you know how to use it in whatever situation you are working but it does require a little getting used to.
Pros: Consistent Output, Durable, Fast / accurate auto-focus, Good range fast sharp, Nice Bokeh, Rugged, Strong Construction
Summary: This an excellent lens which comes at a price, which is not simply measured in dollars. If you want a first class glass, you have to pay the price. It's a heavy lens and requires a sturdy tripod. If you aren't up to lugging serious camera equipment about, then this is not for you. Fast focus, excellent clarity, crisp shots are what you'll get. However, I found that using a 1.4 X Converter results in a soft focus.
Summary: While focusing is slow (under 3 sec) with AF-S/MF on an EM-5 or GH2, the resulting images are excellent. The TC 1.4X doesn't slow focusing and the images are plenty sharp @ F/4.5. The lens support ring is much needed when using this lens, especially with an m43 camera body. I also own the 50-200mm F/2.8-3.5 lens, and while it is optically less excellent than the 90-250mm lens, the significantly lighter and smaller 50-200mm lens gets a lot more use because it is so...
Summary: I purchased this lens shortly before a trip to Hawaii. It is very large and requires its own carrying bag. It is heavy so a tripod is almost a must; I have occasionally used it freehand but more often with a tripod or monopod. It provides outstanding sharp photos at long distances; with the f2.8 stopping action is great (surfers; shore objects from a ship a mile or two off shore).
Excerpt: I use this for wildlife photos and had a great grizzly bear shoot here in B.C., Canada. Extremely sharp, great color, bokeh, and contrast. I shoot it wide open on my E3 and now my E5. I always use a monopod It is the lightest pro lens out there. I've been a Canon shooter for a few years and it's a great system but I just don't use it anymore. I may sell my 5D system since the results of my Oly system are so good. Remember it's always about the glass.
Pros: Consistent Output, Durable, Fast / accurate auto-focus, Nice Bokeh, Rugged, Strong Construction
Excerpt: Tried using it in low light for a figure skating competition. In terms of speed and sharpness, both the 35-100mm and the 300mm are better. Not even close. Save your money and get the 35-100mm and use the 1.4x converter or save up for the 300mm.