Hi Ken,
My wife and me have EM5II and EM1II in Nauticam housing. We share the lenses and ports.
Reason for Nauticam:
Nauticam is very good and, more important for us, it is very common and abundant ("Volkswagen" of UW photographers). I hope that we will be able to upgrade several times when new sensor generations with better dynamic range, S/N ratio and resolution may come in the future (but we certainly will not acquire every new camera model, only in case of substantial sensor improvements, maybe every second generation or so)...
On the short term a cheap plastic housing or the original Olympus housings are cheaper, but when you change the camera body the old ports and extensions may not fit also (the port system between the Oly housings for EM1II and EM5II is, for example, not compatible). In addition the vacuum system, that many cheap housings do'nt have, is a good insurance against flooding. At last, in case you want to have a interchangeable lens system with all options, you will find out that the camera body plus housing is the smaller amount of money you have to spend, the major part goes for lenses, ports etc. (except you save on the optics, but then why not go for compact, this is best for transportation?)...
The only problem I see is that sooner or later Nauticam may remain the only company on the market and have the monopole, if everybody buys Nauticam ...
Of course other products are also very good, but for us this abundancy was the argument.
Ports and lenses:
#1.: Macro: we have Panasonic 45mm and Zuiko 60mm Macro, the Nauticam 45 macroport plus 20mm Mini-Extension (for the 60mm). CMC-1 with Nauticam flip diopter, that we have new since Cristmas - it will be tested in Egypt in February only
.
#2.: Rectilinear WA: Panasonic 7-14mm, Zuiko 9-18mm and Zen DP170-N120. As some others say, it is not the optimal solution. Not because the lenses are rate limiting for optical quality, but because of the corner sharpness. I personally find also the pincushion distortion at 7mm ugly in many cases. If we would decide now we only would have the Panasonic 7-14mm for overwater use, but only #3 for all WA UW and completely omit rectilinear WA (except #4, starting at 12mm rectilinear WA, of course).
In other threads here the WA solutions are discussed and many prefer the WWL1 wetlens that provides similar performance as #3 below (but not the very wide angles as circular or 180o fisheye)
#3.: Fisheye WA: Zuiko 8mm, Canon 8-15mm and Tokina 10-17mm (the latter two with Metabones 1x (seldom 0.71x )adapters and, occasionally the Kenko 1.4x teleconverter). For circular fisheye we have the Sigma 4.5mm circular fisheye with 1x adapter. We use the lenses with the Zen DP170 and the Nauticam 140mm domeports and appropriate extensions/N85-N120 adapters (both domeports have N120 w/o built in extension, so we are flexible). The results are very good and with the Kenko teleconverter all the angles, from circular fisheye to as small as 60o (Canon + 1.4x; same diagonal angle of view as rectilinear 19mm) and 50o (Tokina + 1.4x; 23mm) are covered. The image quality is excellent/very good except the combination Tokina plus 1.4x teleconverter that is noticeable softer as the others (Tokina w/o teleconverter, with 0.71x adapter, even with 1x, is also fine).
#4.: normal range: Zuiko 12-40mm with Zen DP-170. This combination provides excellent image quality but is, of course, not so universal as the Zuiko 12-50mm behind a flat port, where you can mount WA and closeup lenses during the dive and cover the whole range. But nothing is for free, I personally would not like to make 12mm WA photos behind a flat port (my wife was using the Zuiko 9-18mm behind flat port in original Oly housing before - the image quality was a lot inferior even than #3)...
#5.: A note on flashes: we have three Sea & Sea YS-D2 (my wife one since 3 years, the two others since two years), but already two defects: one burned out (never was used over water!) and one with electronics (not possible to switch it on). Both under warranty, but it takes monthes until you get them back. I do not recommend to go for YS-D2...
Wolfgang