Hi Ivan
Not sure where Matt is getting his info from, but AFAIK there is not an adapter for the WP-DC11 housing. The reason for this being the very long telephoto zoom on the G7 resulting in a long physical lens length. This causes the port on the housing to be very long, and when in wide angle mode with a wide angle adapter, the lens is at the back of the port and you get vignetting. The solution to the vignetting is to zoom in, which defeats the object of the wide angle adapter.
This is borne out by the info on ikelite’s website about their housing for the G7 - although their housing allows attachment of 67mm threaded adapters, they don’t recommned the use of wide angle adapters due to the old enemy of vignetting.
Sadly, I don’t think there is a good wide angle solution for the G7 due to its long telephoto zoom.
regards
Graham