Setup info / Tokina 10-17mm with Subal Mini Dome DP-100

I am planning to use the DP-100 Subal mini port I bought this year for the first time on one of these days.

I would like to use it with the Tokina 10-17mm lens.

In Subal website this combination is recommended to be used with 13mm Extension Ring.

However the closest extension ring size that i currently have is 18mm.

Might there be a chance to get good results in case of use of 18 mm of extension ring?

Does anybody have an experience with 10-17mm with 10cm Subal mini dome port?

The size of the extension ring is matched to the position of the housing's aperture. Your lens may sit too far back, with vignetting, with a longer extension. On my Nauticam housing, for instance, the Zen DP-100 dome (designed for the Nikon 10.5mm lens) needs a 20mm extension to fit the Tokina 10-17mm lens. There's a little leeway, although the optical quality can suffer at the edges of the frame. Try your existing kit, and see!

Tim