Over the past couple of months, there has been quite a lot of activity in the forum discussing small dome ports. Seacam has released its 105mm Fisheye Macro port, and Zen, its 100mm dome (both about 4”, for the conversion challenged). Both little dome ports are perfect for fisheye lenses, although crop sensor SLR users have more flexibility due to the availability of the Tokina 10-17 fisheye zoom, one of the most popular underwater wide-angle lenses.
If you’ve felt limited by the large size of your wide-angle dome port, you’ll appreciate the discussion, which includes sample images and in-depth discussion of pros and cons. Discuss: [Seacam fisheye macro] [Zen 100mm]