Close-up lens

Hello,

maybe I could figure this out by myself, but hopefully someone didi it before and would be kind enough to share.

The idea is to take a close-up lens that is usually used on dry land and has e.g. +2 diopter like this one

How it would behave when I would screw it on the port of the housing the same as the wet lenses are used.

Having water on both sides of the lens, the depth pressure is not an issue. It's the optics that interests me.

Thanks and regards.

the optics will work different then in air. Optics are based on light behaviour on glass/air intervals (or water in case of ports), and normal +2 close up lenses are for surface use only.

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the optics will work different then in air. Optics are based on light behaviour on glass/air intervals (or water in case of ports), and normal +2 close up lenses are for surface use only.

 

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That's exactly the point of my question.

I don't care about corrosion on the aluminium ring, pressure is not an issue, thread diameter can be adjusted by step-up rings, etc.

It's the optics that counts. To have e.g. +2 underwater as a wet lens what diopter should be the lens on dry land???

Sorry that my brain can no longer remember the equations, but,

The index of refraction (n) of normal ophthalmic glass is 1.53, that of air is 1 and that of water is 1.33

Looking at those ratios I would say you might need about a +5 dioptor.