This Ikelite 5503.51 Dome Port allows use of the Tokina 12-24mm zoom and other wide-angle zoom lenses in Ikelite underwater housing for Digital SLR Cameras.
The Tokina 12-24 mm zoom lens will focus close enough that adding a + diopter close-up to the lens is not required. The port could also be used with the Sigma 10-20 mm zoom lens but there is no zoom control provided. Lens must be used at fixed focal length.