Sigma 135-400mm f/4.5-5.6

Focusing distance: 200cm / 78.7in
Magnification: 0.19x
Filter size: 77mm
Lens size: ø83.5mm x 189mm / ø32.9in x 74.4in
Weight: 1280g / 45.2oz
Construction: 13 elements in 11 groups
Accessories: Detachable Tripod adapter, Hood, Case

Eddie's take on it

Users report sample variation, back/front focus problems. Pictures at 400mm are pretty soft. It is also slightly soft wide open at all focal lengths, needs to be stopped down.

If you need a long range telephoto, I'd pick up the Olympus 70-300mm instead.

Because the Olympus alternative is so good, not many people bought this for 4/3 and it's hard to find it used.