Sigma 50-500mm f/4-6.3

Focusing distance: 100cm / 39.4in
Magnification: 0.19x
Filter size: 86mm
Lens size: ø95mm x 223.9mm / ø37.4in x 88.1in
Weight: 1830g / 64.6oz
Construction: 20 elements in 16 groups
Accessories: Detachable tripod adapter, Shoulder strap, Hood, Case

Eddie's take on it

The Sigma 50-500mm, nicknamed Bigma, is Sigma's best telephoto zoom for 4/3. If you read online reviews, you will notice that they are all over the place. Some say the lens is bitingly sharp, others dismiss it. This is due to 2 aspects:

Ultimately, the Sigma 50-500mm is a good lens. It is not a bad lens, it is not a very good lens. It's just good. Results you can expect are similar to the Olympus 70-300mm, but with greater zoom range. There are valid reasons to have this sort of telephoto range - for example, if you want to take pictures of a small bird that is not very far away, and you only need them web size.

If you really need it, results with the 50-500mm are going to be better than the 70-300mm with the EC-14 or 50-200mm with the EC-20. I would recommend though to use a shorter telephoto and well, simply try to get closer. You will get better results.

On a 4/3 camera, the bad high ISO capabilites severely limit its possible use, as you need very high shutter speeds to use it at 500mm. If you buy it, best to use it on a m4/3 camera. It works on all m4/3 cameras that support PDAF focusing, such as the E-M1/OM-1 series.

Finding this lens on ebay is pretty difficult.