Sorry for my bad english. About the use of the more lenses that apperar on the market with domes, I am very disappointed with Naticam for the lack of tecnical informations about their ports, and also is for Zen ports. I have a Nex6 housing that is a marvelous done housing and I wont change it with other ones: it is perfectly done and robust and practical in every command, and also the housing for the Nex5N is perfect. But the Nauticam port chart for Sony is old, do not consider some new lenses and lacks of some accessories that would be very interesting.
You know that using a dome is very important that the center of the curvature is in the entrance pupil of the lens. To judge if a lens can work with that port, you mus know the radius of the port: only if you know this number you can judge if the lens is in the right place AND if the minimum focus distance of the lens is ok for focusing the virtual image.
In the Nauticam chart is written that, for the 16 mm pancake lens ( know, not the best lens, but useful and cheap) you can use a flat port (horrific thing, for a 84° wideangle) and the 4,33 dome. I asked to Nauticam the radius of the dome but haven't any answer. I tried practically the 16 with the dome, that the chart sees usable, but discovered that the minimum focus is about 1,5 metres (5 ft), due to the short distance of the virtual image of the dome and the longer minimum focusing distance of the lens. That means the lens can NOT be fully usable with the dome. Also using a +4 diopter, as Rudin sees, is not a solution, but not only because the image degrades, but also because the autofocus became very slow and imprecise. Really, it would be quite useful if you can do a manual focusing, but Nauticam do not procuce a focus gear for 16 mm pancake. Therefore, the 16 mm is not usable by itself. Also, i had the chance to test with the 16 mm with the 36131 Nauticam 3,5" dome for Panasonic, and it works better because , also if the diameter is less, the radius of the dome is longer, and the lens focusing better. But the 36131 is not in the Sony Nauticam Chart.
You would use a Sigma, or other lenses? In the Nauticam chart they are not present. But this not means you cannot use, only means Nauticam do not care. As i read in the before posts, the Sigma 19 works, and the 30 mm do not. A photographer that is skilled about underwater optics can judge if a lens can work if he knows the radius of the dome, but Nauticam do not tells this number, or infos. Just buy before, and throw in the bin later if doesn't works.
Also, for more easy focousing, you can think to buy a bigger port, because the virtual image is more far away ad easy to focus. An example: the 36133 6" dome (for Panasonic) or the 36129 7" dome that the chart points out only for the Sony 10-18 zoom. But you take for sure it works only with 10-18, because is the only lens in the chart. Asking for radius? No answer. Asking via the Italian representative,? No answer also. You mus buy before, then test and if it is not working, throw o resell.
The same for the beautiful Zen domes: I would buy a DP-170 dome, not cheap but marvelous. I emailed many times to know the tecnical caracteristic of the item, but they not answer. You must before buy a 1000$ or so dome, and then test, because you cannot have any thechnical infos.:depressed:
The optics of dome ports are very known from many decades, they are not a secret, or patented. But you can have them. So, I am very disappointed and cannot improve my uw photo gears without "before buy, then test".
It is a pity, because Nauticam and Zen are the best crafters of underwater housing and domes. :depressed: