Hi I have a Nikon D850 with Nikon 8-15mm lens in Nauticam housing. I’ve gotten different responses but does anyone know what extension port I should use with a Matty Smith 12inch dome.

 

I believe it should be 20mm but I was also told 30mm

 

Any confirmation would be great 

I own the port and use the same extension recommended with the 230 port for a verity of wide lenses. So use the recommended extension for 8-15 with your type of housing system. 

Thanks! I tried finding info on your product review article in UwP! Super helpful!