some new lenses from Sigma

This 150-500mm f/5-6.3 zoom looks interesting for nature photography. More here.

Would you believe a 200-500mm zoom at f/2.8? An included converter changes it to a 400-1000mm zoom at f/5.6. If I did my conversions correctly, it only weighs about 35 lbs.!!
No indication as to the price, but you can read more here.