Actually, except for a few flat port housings built for the surfing guys, all of our housings - for the $370 DV camcorders, to the HC3 and FX1/Z1, right though to the $15-$30K broadcast type for VARICAMs and HDCAMs - feature dome port optics. I think corrected underwater optics are essential to good underwater video and we'd be doing our dive customers a disservice if we even confused the issue by offering a simpler flat port case. (If you'd let me get away with a flat port, I could get that new housing out in one long day, instead of two.) We've found over the years that domes are nearly always the best option given extremely high performance and relatively modest cost. The overall image quality is mainly dependant on the quality of the wide angle converter, or the dedicated wide angle in the case of the VARICAM and HDCAMs.
By the way, there seems to an impression out there that the dedicated or built-in underwater optics are somehow inherently superior to the wide angle/dome port combination. Having had the opportunity to build housings for and shoot professionally with every generation of Betacam, Digital Betacam, Ikegami Editcam, and the HD VARICAM and F900 HDCAMs combined with Canon and Fujinon broadcast lenses, from the original High quality wide angle zoom the Canon 6-48mm in 1986 to the Fujinon 4.5-59mm HD zoom in 2006 (ranging in price from $12,000 - $30,000) shooting through dome ports - I can tell you that it just isn't true.
But don't just take my word for it, flip over to the still photo section here on wetpixel and see what they are using with their 8, 12, & 16 megapixel cameras (as opposed to the 1.5 or somegapixels we are working with here on the video side). They all use domes and they are all seem to be acrylic like our standard dome.
If you think somehow motion pictures makes the difference take a look at the IMAX housings - a few years ago we were asked to rebuild the dome port for McGillivray-Freeman's IMAX housing and I was surprised to see that it used the exact same acrylic dome from the exact same manufacturer that we use every day on our housings. I haven't seen Howard Hall's 3D IMAX housing up close, but I know it too has a dome and I suspect that since it is 32" in diameter it is acrylic as well. (We have a glass dome option for many housings, but the main advantage of the glass is that it is easier to get really clean without scratching).
All of the modern camcorders handle the refocusing of the dome just fine with zoom through capability of 5x to 10x (more than enough for most purposes) and full range is easily achieved with a relatively inexpensive add on optic.
We have access to the Fathom optics, but it just hasn't seemed worth it on the HD cameras up to now, although we are looking at it more seriously for the Panasonic HVX200 since the large size of its lens means the wide angle converters are quite expensive also so there is not as much difference between it and the Fathom-type dedicated underwater optic.
One of the things I would like to see on these forums is some fact-based examination of the differences. That is: use some actual charts in a side by side comparison in controlled conditions with the same camera. And not comparing a 100 degree optic with a flat port, or 80 degree optic - but using a comparable high quality wide converter (i.e the $500 - 1000 or so wide converter - which by the way can be used above water as well) and a proper dome and see if there is really any difference, or a significant difference that justifies the cost differential. We've done those kinds of tests with the broadcast lenses over the years, but not recently with the prosumer HD type camcorders. I know what my suspicion of the results will be, but I'd be happy to be convinced otherwise.
