I had a chance to shoot with the Olympus E-PL3 camera and Nauticam NA-EPL3 housing while diving with SPLASH DIVE CENTER (splashbelize.com highly recommended) in Placencia, Belize. I spent several days diving in the Silk Keys after a recent algae bloom.
My Nauticam NA-ELP3 housing was equipped with the Nauticam 4.33 inch dome port which I used with the Panasonic 8mm F/3.5 fisheye and the Olympus 12mm F/2.0. I found both lenses to be very sharp behind the dome with little corner softness. Both lenses focuses very close (to the dome) which allowed me to get within inches of the Lionfish.
The 12mm is a great lens for fish portraits and larger animals like the Loggerhead turtle feeding on lobster remains which had been dumped near the keys by local fishermen. I also took some split shots during lunch on one of the local keys. The smaller dome and 12mm lens combo set at F-22 using ISO-200 gave we a shutter speed of 1/160th in the bright midday sun light. The other 12mm images were also exposed at ISO-200 and 1/160th ranged from F/7.1 to F/9 with two Inon Z-240 strobes for fill lighting.
The Panasonic 8mm fisheye lens is very well suited to underwater photography but requires time to master due to the wide angle of view. When I started using fisheye lenses underwater I ended up with my fins, strobe heads, strobe cords, diver parts and more in the frame. Fisheye lenses because they are so wide often include the sun particularly when shot vertical.
This can cause the sun to burn a hole in the image as in the upper right corner of the gorgonian image. With the Jelly shot I put the sun to my back to avoid the problem and with the vase sponge I got low and close putting the sun behind the sponge. These lenses also distort objects with straight lines like wreckage, large animals and more.
Because the lens is so wide it may fool the auto focus system as well. See in the photo below how the lens in auto focus chose to focus on the water drops on the surface of the dome (yes, that is how close these lenses focus) rather than the much larger boat.
The Olympus 12mm and the Panasonic 8mm fisheye lenses are not cheap, however they can both be used with the same Nauticam 4.33 inch dome port. These lenses give two distinctly different wide angle options and offer first class sharpness across the entire frame. Both lenses are very small and well suited for travel as is the Nauticam NA-EPL3 housing.