If that is a Ikelite housing with 67 MM threaded port you do not need an adapter, you just need an Inon Type II 100 WAL or Epoque or Ikelite lens. These lenses all have about a .56 X magnification. The resulting FOV is about 90 to 100 degrees and sometimes less depending on the camera etc. That is a big improvement over the standard FOV of about 45 degrees. Inon also allows their lens to accept a dome port that will expand the FOV to as much as 130 degrees, about .46X.
I built my own 67MM Ikelite port adapter for Inon AD bayonet lenses, these lenses will not work with the 7070 however. The adpater threads into the 67 MM thread and then locks so that the Inon AD lens can be installed. You do not need such a thing.
BTW, the adapters Ikelite makes are for their 47 MM ports, I think your housing is the 67 MM. The threaded Inon lenses will NOT require an adapter, the bayonet mount lenses will and there is no such thing except for the one I made.
This is not your housing but it is a typical Ikelite threaded 67 MM port:
Here is an Inon 165AD FE lens on my homemade port adapter installed into the 67 MM threaded port, about .40X:
My 67 MM port to Inon AD adapter in the port:
Again, you cannot purchase this, Ikelite does NOT make one and in addition I don't think the AD lenses are optically compatible with the 7070 due to the lens diameter of the camera.
I believe the lens that would work best with the 7070 is the Inon 100 28AD. This lens is meant for lenses with a native greater than 35 MM focal length. However, nobody makes an adapter. FYI, Inon AD and Inon 28AD are different types of bayonet mount. Since the Inon America web page is gone now, well, all of this used to be explained there.
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