Lens Focusing Distance - How Does It Change Behind Flat Ports?

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LaGa

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Hi all,

I am trying to figure out which lenses I should get/pack for an upcoming trip.

I will be using an a6000 in a meikon housing. Considering to try out a macro lens for the first, I am wondering about practicalities.

For a given lens I get a minimum focusing distance. Now, a flat port on the underwater housing will affect the optics, basically leading to a magnification, or increase in (effective) focal length of the lens. Please correct me, if I am wrong here.

What does that mean for the minimum focusing distance with that lens? Will it increase and if so, by how much? Or will the flat port act almost like a diopter?

I guess that will all depend on the focal length and minimum focusing distance in air. I would be happy for any indication, from personal experience with a specific lens to a physics tutorial that allows me to calculate for myself. Relevant links are welcome, too. :)

Cheers,
Lars
 
https://www.shearwater.com/products/teric/

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