Finally catching up on Underwater Photography Show episodes and got to the one about curved ports for wider macro shots.

In the comments, @Alex_Mustard mentions using the Sony 50mm with the Nauticam 4" port and a custom 16mm port extension.

Unfortunately the one he mentions has been discontinued. There is a N85 version available which should still work with the 50mm macro, but Nauticam's N100 to N85 adapter (which would have been perfect as its 20mm) has also been discontinued.

Are there any other options other than going fully custom?

5 hours ago, shokwaav said:

Finally catching up on Underwater Photography Show episodes and got to the one about curved ports for wider macro shots.

In the comments, @Alex_Mustard mentions using the Sony 50mm with the Nauticam 4" port and a custom 16mm port extension.

Unfortunately the one he mentions has been discontinued. There is a N85 version available which should still work with the 50mm macro, but Nauticam's N100 to N85 adapter (which would have been perfect as its 20mm) has also been discontinued.

Are there any other options other than going fully custom?

I believe you can still get the port but they are special order.

Have a look on UWVisions (Nauticam UK distributor) run by Dr Alex Tattershall and he maybe able to help.

I am looking at doing the exact same thing 👍

I have been testing the Sony 50 macro with a "curved port" (aka a dome port) using my A7RV and A7CR with the Nauticam N120 140mm dome. I estimated the EP at 43mm at infinity and 45mm at 1:4 (behind the dome it will be always focusing close because of the virtual image).

With a 25mm adapter (= extension), I calculated the alignment is almost perfect.

Land tests extol the IQ of the 50 macro, and criticise the slow AF. However, almost all available tests are using older Sony cameras, and there seems to be some improvement with the latest bodies.

There is no need to get the port mentioned, although it may be easier to light close-ups because of the small size. On the other hand, I have not seen a figure for the radius of this port, so we have no starting point to calculate the correct extension to best align the optical centre and the lens EP - and I believe you should always try to align a dome and lens as best you can.

I have posted results in other threads, but to recap:

Good:

Improvement in IQ (overall sharpness right across the image) is astonishing.

Not so good:

There are AF issues when using AFC with tracking and medium spot (my preferred setup for all my photography), presumably because of the 10 year old lens' primitive AF motor (compared to the latest zooms). The AF adjustments required when tracking focus on the VI are minute. But it is doable - if you give the camera a little extra time to "decide" it is in focus before you take the photo. You will still get the occasional failure - but nothing as bad as trying to use the MFO with Sony 90 with AFC and tracking - see the older MFO thread.

Next step is to go backwards and test AFS and AFC without tracking, and see how that compares. I would rather not, but I suppose it will be OK for subjects which are centre frame.

Even so, for general use I wouldn't go back to a flat port for this lens (only for the 90 - which I haven't got to work well behind a dome).