Confused about dome and lens setup

I have the Tokina 10-17mm lens and an Aquatica 8" dome port. Having only used the whole setup on roughly 10 dives, my (beginner) pictures look fine to me, but am I missing something? I've been reading Lou f's post and I'm feeling very uneducated! Should I be using an extension ring or a diopter to give me more versatility with my lens?

Thanks.

Can't use a diopter on that lens.

If your pictures look fine, then relax.

If your pictures look fine, then relax.

Rich:

An 8 inch dome with the tokina is a very good combination for almost everything.

Hi Rich, or should I say Mr Drift , we recommend a small extension ring between the 8" dome and housing to improve the already good performance in the corners when shooting at large aperture, it is not obligatory and the lens behaves very well without it, the corner softnesss only being noticable if you pay close attention to the very edge of the image.

Cheers