I recently had a question from a Seacam shooter as to whether he should use the Superdome he already had, or buy the Wideport which is optimized for the 20mm.

His objective was to get away from shooting the 15mm lens on the Nikonos to achieve critical focus and SLR viewing, but also to minimize the amount of gear for travel. (Since the 20mm is 94 degrees behind a dome, and the Nikonos 15mm is 94 degrees as well, this was the optic he was considering).

The test below shows the 20mm with a Superdome and no port extension. In my opinion it rivals the Nikonos 15mm. Granted, the small size and convenience of the Nikonos is compelling, but here we are examining optics only and the 20mm with Superdome is quite nice. However, for absolute stunning resolution corner-to-corner, consider the 18mm Nikkor behind the Superdome with no port extension. Photos below illustrate both the 20mm and the 18mm on an F100 Seacam housing with Superdome.

18mm	20mm
Goatfish in Bonaire. Taken with Nikkor 18mm and Superdome on Seacam F100 housing.	Azure vase and orange elephant ear sponges in Bonaire. Taken with a Nikkor 20mm and Superdome on Seacam F100 housing.