Basic question -- Do I need a dioper??

I am new at all this.

Bought the Ikelite Housing with the 8 inch dome and a Tokina 10-17 lens.

About to use it for the first time in a couple of weeks when someone asks me.....................are you sure you do not need a diopter?

No idea if I do or do not need it. Help!

I am new at all this.

Bought the Ikelite Housing with the 8 inch dome and a Tokina 10-17 lens.

About to use it for the first time in a couple of weeks when someone asks me.....................are you sure you do not need a diopter?

No idea if I do or do not need it. Help!

No you do not need a diopter for this lens. In fact it does not have a threaded mount in the front for a diopter. The lenses that you may need to consider a diopter for are the rectilinear wide angle lenses like the Nikon 12-24 that are not able to focus close enough to focus on the virtual image created by the dome port, the diopter allows these lenses to focus closer. The 10-17 will focus on the glass of your domeport.

exactly what Jeff said