Diopter for WA?

Hi there. Would you recommend I use a diopter with my Canon 16-35 f4 lens? I use it with either the Aquatica 9.5" glass dome or the 8" acrylic dome.

Any advice appreciated.

James.

Check out the sea & sea internal correction lens

You don't need a diopter for this lens, as it focuses close enough by itself. A diopter is used for WA if the lens can't focus close enough to focus on the virtual image formed by the dome which is about 3 dome radii away from the dome surface. If the lens can already focus on this a diopter does not help.

The S&S lens helps by bringing the corners into focus, the virtual image is curved and the corners are closer and you need to stop down to bring them into focus. The S&S lens helps by partly correcting this curved image so you dont need to stop down as much to bring the corners into focus.

Many thanks for the info guys, much appreciated.