The WD-3 Wide Angle Dome provides mid-range angle of view with no vignetting (dark shadows in the corners of the image).
The W-30 Wide Angle Lens, INON UWL-H100, and other 67mm threaded wide angle lenses, provide a wider maximum angle of view. Because these are separated from the camera's lens by glass, air, and water, some vignetting and edge distortion will be present. These effects can be reduced or eliminated by using a smaller aperture, zooming in slightly, and/or cropping in post-production.
External macro lenses with 67mm threads from INON, Epoque, and other manufacturers, can be attached directly to the front of the housing's port.
The DC2 6" Dome Port #6402 offers the best of everything: wide angle, macro, and over-under all on one dive. This special dome port replaces the housing's standard port and provides sharp 24mm wide angle and is perfect for split shots (half-in, half-out of the water). Approximately 3/4 of the camera's zoom range is usable behind the dome and macro images can be captured with the dome installed.