The Sigmas are good lenses if you get a good copy. The trouble is they can have varying build quality. An awesome lens is the 17-70 mcro, very sharp and fast.
The 10-20 is good above water, but seems to suffer for soft corners when used uw with a dome.
Jack
The 10-20 is good above water, but seems to suffer for soft corners when used uw with a dome.
Jack