Practical size and weight differences between different camera formats

50 minutes ago, nudibranco said:

my 9-18mm  lens requires a 4" nauticam port (100mm).

 

I saw that listed in the NA port chart. Any idea how it performs in that port compared with e.g. a 7" port?

5 minutes ago, strandbygaard said:

I saw that listed in the NA port chart. Any idea how it performs in that port compared with e.g. a 7" port?

I cannot say how the zuiko 9-18mm performs behind the 100 port, but we have the lens. My wife was using it first behind a flat port (also recommended as a solution by Olympus) and now is using it behind the Zen DP170 (170 mm) port. The IQ is no comparison, flat port @9mm is ugly...

Wolfgang

My parents are using the 9-18 in a Subal 6inch dome. Corners are alright but not great, although Subal doesn’t provide any data about extension length. My 8-18 in 7 inch dome is clearly better. 

The 9-18mm in the 4" nauticam port works better than most other ports.  It is a semidome and much more compact than the 7" one.  However I did not have a chance to test the 7" port.  The flat parts are terrible as expected.  

However a +2 achromatic addon to the lens inside the port will improve the corners considerably if you want best quality below F8.0.

Frankly I hardly use it and much prefer the 8mm fisheye lens which focuses so close to get CFWA capability.  I can even get a reasonable nudibranch picture with the 3.5" dome port from Nauticam.  And it is a VERY sharp lens.  You can defish it if you do not like fisheye distortion.