SlipperyDick

NOTE: The Aquatica +10 diopter lens is a 2 element achromat (as far as I can tell - but correct me if I'm wrong, Jean), while the SubSee +10 is a 4 element achromatic system. Spreading the +10 dioptric strength over more elements allows significantly less edge distortion to be present.

 

Keri

No problem, Alex - thanks for giving that article a shout-out

could you clarify what it means by sealed optics? from my understanding it's the lens elements sealed in air? Aren't the FIT and Inon diopters dual element lens that are also sealed?

When I say "sealed optics", I mean that the lens' refractive (curved) surfaces are permanently sealed in air, so they never come in contact with water. This is how the MacroMate and SubSee are constructed - underwater, they perform exactly as they do on land. I'm not sure about the MacroMate, but the +10 diopter SubSee is actually a 4-element lens system.

The FIT lenses are most likely dual-element achromats, but are not sealed optics (again, someone correct me if I'm wrong!). Water directly contacts their refractive lens surfaces, so they lose most of their power underwater.

The Inon lenses are a combination of sealed optics and water-contact optics. They have 2 curved internal surfaces which are permanently sealed in air, but their external surfaces are also curved... so, a much smaller portion of their power is lost (the Inon UCL-165 goes from a +7.4 on land to a +6 underwater). However, they are not achromats (so are prone to chromatic aberration), and have much more edge distortion than others.

I hope that cleared things up for you, Alvin!

Keri