I got my Sigma 150-500mm rental from LensProToGo today! I got it early to practice before I visit the San Diego Zoo this weekend. I must say - it is a beast. Each of the lenses I own can fit inside the Sigma's lens hood. On my DX-format Nikon D80, the effective range is 225-750mm.
I took it down to my usual proving grounds near the beach in Santa Monica and took shots at sunset, which was quite lovely. Just before sunset, what appears to be every single seagull in the city decided to fly around the pier. It was quite a sight, I almost missed it.
So how much zoom is 500mm? I was standing over 1.2 miles (1.9 km) away from the pier when I took this shot.
From One/Day Project, Year 3