Hi etudiant,
As I mentioned on another post today:
"For whatever reason, the idea hasn't caught on that your eyeglass prescription plays a major role in determining your eye relief needs. In general, near sighted folks can get away with shorter eye relief than far sighted people. The optical explanation has to do with how the prescription lenses move the effective location and size of your eyes' entry pupils."
Depending on the prescription involved, we're talking about 3-5mm.
Being 3.5D far-sighted, usability for me begins with ER ≥ 18mm.
They are in the optics business and peddle expensive products. It's only fair that they provide what the population needs.
Ed
Thanks for that insight.
Explains why 13-15mm is fine for me at -4D but no good for some others.
Seems obvious now that you point out why, the image of the eye,
but I blamed it on glasses frame size only before.
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