Nauticam optical glass dome ports are finely grounded to the highest standard of precision and represents the state of the art manufactering and optical technology. It features in total 4 sizes to cater different lens. And 230mm optical glass wide angle port is particularly good for both DSLR ultra wide angle lens and fisheye lens for example:
Nikon AF-S NIKKOR 16-35mm f/4G ED VR
Nikon AF Fisheye 16mm f/2.8D
Nikon AF DX Fisheye 10.5mm f/2.8G ED
Sigma 15mm F2.8 EX DG Diagonal Fisheye
Canon EF 16-35mm f/2.8L II USM
Canon EF 16-35mm F4L IS USM
Sigma 15mm F2.8 EX DG Diagonal Fisheye
Canon EF-S 10-18mm f/4.5-5.6 IS STM
Specifications:
Body construction: anodized aluminium alloy
Port shade: BS/Aluminium alloy
Coating: multi layer braod band anti-reflective coating inside.
Depth rating: 40m
Weight: 1.63kg
Port mount: N120
Radius of Curvature: 120mm