Dome Ports Info

Hi everybody, I need to ask about dome ports. I have a Housing i have that has a dome port. Its not made for my camera. Just wondering when lining the camera up with the dome port. I am it directly in the center looking out but wondering about how close or far away the front of the lens has to be to the dome?

Or if it doesnt even matter at all?

Thanks everybody

Read this:

http://wetpixel.com/i.php/full/proper-dome...-and-placement/

its a bit technical but the diagrams are helpful.

Typeing "nodal points" into the Wetpixel search engine will bring up lots of posts on this subject for you to look at.

The camera is a Video Sony Hdr cx7 the housing is a Equinox pro 6. the housing is for a different sony camera so this is why I am asking.