Barmaglot,
Yes, you are correct, those are exactly the issues that need to be dealt with. Until I get some of the gear to measure, it's hard to say what will work.
In regards to the N85 nomenclature, yes it does stand for the mm size of the housing opening for the ports, but not the ID of the ports themselves that the lens must fit through. The first port flange design (that the 4.33 is manufactured from) used parts and mechanical connections , which has an ID of 70mm. The mini-extensions that followed use the same design, but Nauticam enlarged it by 2mm to a 72mm ID. The latest Nauticam mono-flange design design (no mechanical parts/connections) that they created to accommodate fatter lens and gears (like the S10-18) is a whooping 77mm. Unfortunately, if you buy the 4.33 and mini-extensions today, they still incorporate the older design. It appears Nauticam doesn't don't want to redesign their machining process for earlier ports. Because of this, I've had to make custom zoom gears out of 70 x 1mm titanium tubing with timing belts for the Ziess 16-70 and remove the shade mounts on the Zeiss 12 and Sigma 16 f1.4 to fit the 4.33. Otherwise, all the lens (except Z12?), including focus/zoom gears, would have fit into the N85 4.33 if it had the newer 77mm flange mount, perhaps even perhaps the S10-18. However, being a rectilinear zoom at 10mm most likely wouldn't work with the 4.33. As you correctly pointed out, most WA rectiliniers do not play well in the corners, especially extreme WA. Alex Mustards article and formula on using small micro domes for rectilinear WA's just barely met the specifications for the Z12 and the 4.33. I was surprised I got such good performance in this respect. Just lucky the optics worked, especially with CFWA. Fitting the Z12 into the 4.33 was an engineering task that Zeiss helped me with.
As far as lens design goes on the new Sony G, as you pointed out, the length at it's long end might be problematic. However, both the Sony 18-55 Kit and Zeiss 16-70 extend their lens barrels in the same manner. The Zeiss being a longer lens at 16-70mm has an extension of 44mm from it's 16mm position and this works perfectly in the 4.33: the 16mm end is positioned optically correct for WA with no vignetting and the long extension comes within 2mm of the face of the dome which works out perfect for using a diopter for SM. However, for whatever reason, the optics of the Z16-70 do not play well with my CMC-1 or other high power diopters, even though a +5 works fine. The Sony Kit 18-55 doesn't have these issues and works perfectly with the CMC-1 in all respects, so I tend to use it over the Z16-70 for a single dive lens for CWFA and SM, even though I miss the extra 2mm of WA. Moreover, the Sony kit has a very short minimum focusing distance, compared to the Z16-70, which gives it an advantage in CFWA. The S16-55G would be perfect if it had a similar minimum focus distance. It would give perhaps the same macro IQ as the much heavier S90G M at a more medium macro range and provide razor sharp corners at 16mm WA. As you pointed out on your above lens post, the longer S90 macro is great for SM, but one has to put a lot of water between it and the subject if shooting anything larger.
Presently, the 73mm girth of the new S16-55G will require a two part port since it doesn't appear that Nauticam will change their machining design of the 4.33 port. I may call the dealers and have them check for me since it's been a while, but last year when I checked, they said the flange was still the same design with the ID at 70mm. The 50mm extension of the S16-55G you refer to might be handled okay by the N120 4/4.33 dome since it's only a few mm more than the extension of the Z16-70. Until I get my hands on the new lens, I won't know what the actual extension is? The back of the new S16-55G lens will fit through the mini-extensions, so it's possible to fine tune the lens position in the port by the use of mini-extensions at the housing body. I'd love to see Nauticam create a port similar to their 4" semi-WA port # 36137 (for the S18-55 Kit with it's attachable 67mm swing mount for macro) for the new S16-55G. It would solve the corner and extension issues you speak of and make things a lot simpler.
I just don't have the funds to play around with the modification idea for now, as a new lens and adapters would cost $1,900 +. Not to mention the engineering of getting the knobs on the adapters to work with the zoom and/or focus barrels. The housing gear system can only handle a 70mm OD which works with the titanium tubing and narrow lens, but it cannot be adopted to fatter lens. If I come across some inexpensive used gear, I might have a go at it with the two part port system as mentioned earlier, but for now the set-up I have works great.
I apologize for the length of this response :-) , but it addresses some of the technical issues for such modifications if one is interested in a small travel rig with the best Sony lens. Those who want more specific information, please contact me directly through the message board.
Marshall
. With the EM-1 MkII the image quality is very close particularly if I do my bit and expose well and it all just works.
