C&C compact dome port diopter question

Does anyone know what diopter lens you need for a Nikon 18-70 lens behind a See & Sea compact dome port?

Cheers in advance!

Jim

Hey Jim, how goes it?

I would think the +4 is what you want. That is what most people use. They should come in packs of +1, +2, and +4. Give them a try, but the +4 will give you the closest focus and shouldn't affect your far focus too badly

Hi Mike

It goes well thanks! You not going to DEMA? (I ain't)

I have a +4 somewhere about. I'll see if it fits on the lens. If not, they're cheap and easy to come by.

TTFN

Jim