Ikelite has released two new 6-inch dome ports with extended zooms for mirrorless cameras. One with its dome port extended .375 of an inch and the other extended one full inch. MSRP is $375 and $400 US respectively. A dome shade is expected to be available in late 2017.
From the Ikelite website:
“*An optical-grade acrylic 6-inch diameter dome allows you to fully take advantage of the angle of view of your lens. Acrylic produces virtually identical image quality to glass yet is much lighter weight and easier to pack. Our unique zoom sleeves are simple and affordable. Zoom sleeves are particular to the lens for proper operation. Refer to the appropriate port for your housing to determine compatibility.”
Find full details here.