Correct Specification for Reader Mask Lens???

[Doctor Rig]

Should the focal distance of a 1.75 diopter pair of cheater glasses have the same focal distance as a 1.75 diopter reader mask (in water)? If not the same, what reader mask diopter correction would be needed?

I’m confused, my street glasses have a reader correction of +1.75 diopters. I bought a DGX REN mask with 3.00 reader lenses, and I have found the underwater focus distance is about the same as my 1.75 diopter street glasses.

I would like to be able to read my gauges and camera at about 8 to 9 inches, not their present 15 to 18 inches that I’m currently experiencing with my DGX 3.00 spec reader mask. Could my DGX mask have a much lower actual diopter rating than its 3.00 rating? Or what do I need?

Any input or assistance in selecting/specifying a new reader mask with focus distance of 8 to 9 inches would be greatly appreciated!! Thanks!!!

 

[Hatul]

Should the focal distance of a 1.75 diopter pair of cheater glasses have the same focal distance as a 1.75 diopter reader mask (in water)? If not the same, what reader mask diopter correction would be needed?

I’m confused, my street glasses have a reader correction of +1.75 diopters. I bought a DGX REN mask with 3.00 reader lenses, and I have found the underwater focus distance is about the same as my 1.75 diopter street glasses.

I would like to be able to read my gauges and camera at about 8 to 9 inches, not their present 15 to 18 inches that I’m currently experiencing with my DGX 3.00 spec reader mask. Could my DGX mask have a much lower actual diopter rating than its 3.00 rating? Or what do I need?

Any input or assistance in selecting/specifying a new reader mask with focus distance of 8 to 9 inches would be greatly appreciated!! Thanks!!!

There are three factors that make reading glasses different from mask bifocal: looking through water, distance from the eye and distance to the gauge being much less than reading a book. My experience is that I need much more correction in a mask bifocal than my reading glasses because we read our gauges very close. So I usually read with +2.5 diopter on land but my optimal mask bifocal is +3.5.