I read on another site that: 1/2 the cylinder measurement + the sphere measurement = diopter strength. Because I have a lot of astigmatism this changes the measurements quite a bit (-3.25 cylinder, -3 sphere). Has anybody else used this equation to determine the strength in buying goggles? I read on another site that: 1/2 the cylinder measurement + the sphere measurement = diopter strength. Because I have a lot of astigmatism this changes the measurements quite a bit (-3.25... » Read More I read on another site that: 1/2 the cylinder measurement + the sphere measurement = diopter strength. Because I have a lot of astigmatism this changes the measurements quite a bit (-3.25 cylinder, -3 sphere). Has anybody else used this equation to determine the strength in buying goggles? « Show Less
107802
That equation is correct... it is called spherical equivalent. With a -3.00 sphere and -3.25 cylinder, your spherical equivalent is -4.50. Keep in mind this will give you pretty decent vision - good enough to see at a reasonable distance, but this will not be equal to a full spectacle prescription. I am an optometrist.
40139
That's the method we used when buying my daughter's goggles. She ended up with -3.625 (R) and -4.25 (L) so we split the difference with a -4 prescription. She says they work well enough for her, and she has to be read a white board to get her workout during swim practice.
107803
hi, none of us are opticians. I'd give them a call and ask. That way you'll get a pair of goggles that you can use to read underwater - haha - but seriously, I was thrilled when I could see clearly underwater. It's worth the effort!
2263147
with out the 3x magnifier I wanted the two dot easy to see . with out the 3x magnifier over two dots hard to see them . yeah with 4 dots and no ◾3x magnifier looks like a straight line. I dint want the weight and pay the extra cash. my friend has the 4 dot and 3x magnifier really nice set up. hope this helped you :)
64369
Because of the difference I would suggest buying 1 pair in each of the diopters you need and swapping out the lenses. For me the difference was only 1 point so I went up a half. They've worked out great.
1746
That is the strength of the reading glass. The higher the number the greater the magnification. It is not at all about the size as it will fit your head.
57695
The goggles only come with a negative value which is for near-sighted. Mine were totally useless, terrible distortion, I could not use them and was given bad information by customer service. When I complained, iI was treated rudely. They offered no positive numbers for far-sighted
1193218
The 1.25 dimension is the standard telescope eye size for most scopes. I to have a C90 and purchase a "hybred-diagonal" (.965 to 1.25). This allows me to use all of my 1.25 eye pieces on my C90. Hope this helps.
57696
Do you mean size or prescription strength? As mentioned below they are adjustable in size, although very difficult to change size of nose bridge. As for the prescription, they come in negative values. My prescription is different in each eye. -2.75 and -3.75. I picked one in the middle -3.00. They are great.
1177291
Depends on what your prescription is. The camera has a built in -3.0 to +1.0 diopter adjustment. You want to buy the one that will allow you to match your prescription.E.g. If you wear +2 prescription, get the +2 and dial it down by 1. You would only need the - if you have to go further than the -3 that is built in. However, I have found that I do not use the diopter. When I have my glasses off, the images on the LCD are blurry. So I shoot with my glasses or contacts, so I can still view the images on the LCD.Hope this helps you decide.Chris
1679461
Its infinitely variable as far as I can tell. Its like twisting a knob. I don't use this very often, only on one particular lens. I almost forgot about it. Thanks for reminding. No issues with this at all. Just guesstimate only for aperatures.
1090074
look for the size of a particular glass in the product description (on Amazon of course). you will see numbers like this 55-18-14555(mm) will represent the lens width18(mm) will represent the bridge width145(mm) will represent the overall length of the armthese numbers change with the models - GR003, 004, and 001, etc. I took a pair of sunglasses that fit me well on the brigde of my nose and the arms length and measured them. Prescription glasses may have the measurements on the arms already. Google how to properly measure for glass frames and then find your match of Gamma Ray. The Gr001-C1 matched mine, although I think I got the bridge a mm larger just in case. look for the size of a particular glass in the product description (on Amazon of course). you will see numbers like this 55-18-14555(mm) will represent the lens width18(mm) will represent the bridge width145(mm) will represent the overall length of the armthese numbers change with the models - GR003, 004, and 001, etc. I took a pair of sunglasses that fit me well on the brigde of my nose and the arms length and measured them. Prescription glasses may have the measurements on the arms already. Google how to properly measure for glass frames and then find... » Read More look for the size of a particular glass in the product description (on Amazon of course). you will see numbers like this 55-18-14555(mm) will represent the lens width18(mm) will represent the bridge width145(mm) will represent the overall length of the armthese numbers change with the models - GR003, 004, and 001, etc. I took a pair of sunglasses that fit me well on the brigde of my nose and the arms length and measured them. Prescription glasses may have the measurements on the arms already. Google how to properly measure for glass frames and then find your match of Gamma Ray. The Gr001-C1 matched mine, although I think I got the bridge a mm larger just in case. « Show Less
1211051
What I did was, using a set of metric vernier calipers measure the outside diameter of bothe the Ocular lens (eyepiece) and the objective lens. Then using the Butler creek measurement table, chose the size as close too or slightly smaller than that measurement. I too had issues with finding what I needed and I did have to surf about a bit, but I finally found a table that had all of scope cap sizes and measurements. Hope this helps
1558346
I ordered a pair for myself and 1 pair for each of my sisters in new mexico and texas. We all decided they were not user friendly for us. I don't know the strength but I can tell u this, you cannot see anything unless u hold the item about 1/8th of an inch away from our eyeglasses (we all wear glasses. we were hoping we could get splinters out but we all decided that they would not work for that either. all 3 pairs were thrown in the trash. they just did not work for us. hope this helps u
998685
It says"Magnifier 2 5x ...". I believe the 2 is just part of the product name, there is no decimal point. A 4" lens diameter can't be 5x, they just can't make them. I even asked my eye doctor about ordering one from him. So I think the lens is a 1.5x with a 3x inset as the lower information on the page description says,. I sent mine back as the one I bought at a fabric store was better. I think you could find a 2x or 2.5x in a large lens with a 6x inset somewhere else. The around the neck batteries wear out very fast so you need rechargeable batteries for cost reasons.
1683132
It depends on what you'd eyeglass prescription is. You should check with you Optomotridt and find out what your prescription is and then get the diopter closest to that.Rich Signorelli
1025376
Sorry, but I don't have an expert answer. Here's what I did. I simply measured, with a very accurate ruler the exact outside center cross distance on the lens. No matter if it measures in inches or metric, just Google the number for a conversion. Worked perfect for me on the first and subsequent orders.. The covers fit perfect, are very well made and I'm very happy to have this protection for all of my lenses. Hope this "grass-roots" method works for you. Bob D., Maine
1591412
This is a very complicated answer. I defer to this link.http://www.astroadventures.net/cohen/articles/Wear%20or%20Not%20to%20Wear%20Glasses.pdfWhether you wear glasses or not, each lens that you use requires that your eye be placed at an optimum distance from the lens. Wearing glasses prohibits one from getting one's eye close enough to enjoy the full field of view with some lenses but not others. The preferred method is to NOT wear glasses and each person must adjust the focus for the best clarity. If your wife has an astigmatism, you can switch to higher eye relief lens while wearing glasses or purchase Televue Dioptrx Astigmatism-Correcting Lenses while not wearing glasses. Have her optometrist make her a monocle. This is a very complicated answer. I defer to this link.http://www.astroadventures.net/cohen/articles/Wear%20or%20Not%20to%20Wear%20Glasses.pdfWhether you wear glasses or not, each lens that you use requires that your eye be placed at an optimum distance from the lens. Wearing glasses prohibits one from getting one's eye close enough to enjoy the full field of view with some lenses but not others. The preferred method is to NOT wear glasses and each person must adjust the focus for the best clarity. If your wife has an astigmatism, you can switch to higher... » Read More This is a very complicated answer. I defer to this link.http://www.astroadventures.net/cohen/articles/Wear%20or%20Not%20to%20Wear%20Glasses.pdfWhether you wear glasses or not, each lens that you use requires that your eye be placed at an optimum distance from the lens. Wearing glasses prohibits one from getting one's eye close enough to enjoy the full field of view with some lenses but not others. The preferred method is to NOT wear glasses and each person must adjust the focus for the best clarity. If your wife has an astigmatism, you can switch to higher eye relief lens while wearing glasses or purchase Televue Dioptrx Astigmatism-Correcting Lenses while not wearing glasses. Have her optometrist make her a monocle. « Show Less
1679463
Its infinitely variable as far as I can tell. Its like twisting a knob.I don't use this very often, only on one particular lens. I almost forgot about it. Thanks for reminding.No issues with this at all. Just guesstimate only for aperatures.