OT - Graduated Mask

Hi all, sorry to post this litte off topi not photography related.

I'm goin' to buy a graduated mask, i'm a little shotfocussed and outside the water i have -1.75 and -1.25 (very little astigmatism that i can think about not correcting) i've been told that i have to decrease the correction of 25% while on my beliving air whater interface is a positive lense so i was thinking about increasing the correction.

Anybody that can clarify this point ?

P.S.

I can't use contact lenses.

Hi all, sorry to post this litte off topi not photography related.

I'm goin' to buy a graduated mask, i'm a little shotfocussed and outside the water i have -1.75 and -1.25 (very little astigmatism that i can think about not correcting) i've been told that i have to decrease the correction of 25% while on my beliving air whater interface is a positive lense so i was thinking about increasing the correction.

Anybody that can clarify this point ?

P.S.

I can't use contact lenses.

Call Linda at Prescription Dive Masks in San Diego. She is a diver and an optician and has made several masks for me with great results

http://www.prescriptiondivemasks.com/

I am not affiliated with them except as a happy customer.

Bill