Excerpt: I used the 90-250 w/ 2x teleconverter (1000mm) to shoot Terry Fator and his puppets from a 150'. It yielded a great, super sharp bust shot for projecting on his show. However, it has communication issues with the Lumix GH4. Iris does not function correctly in manual mode.
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.
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.
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.
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.
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.