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!
1340325
The first number is the power of the lens, that is how much it will magnify the image. The second number represents the diameter of the lens in mm. They work together to calculate a number called the "exit pupil" or "exit ratio". Take the lens size and divide it by the power to get this number. The higher the number, the brighter the image. For example, 10x50 will give an exit ratio of 5.0, 8x42 would be 5.25, 10x42 would be 4.2. In my opinion, the exit ratio is more important than the power. My favorite binoculars are 8x50 (6.25) but I also just bought 10x50 as a gift who is delighted with that configuration. Stay away from high-power binoculars. They, for me, are too hard to keep steady due to the high magnification. I hope this helps. -Norm
1870387
Using another spyglass viewing a yardstick and doing a little math I came up with 145' at 1000 ft which would be 450' at 1000 yds. A quick test against my Mom's similar $135 device, including the 10" focus ability, showed no visible difference to me. I do wish it had a rubber eye cup, though.
1177288
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
1359655
To get the answer that you are seeking; I would go to www.nacdrops.com to get a definitive answer. My understanding of this product was specific to the eyeball penetration. Hopefully this will aid you in what you are requesting.
1503374
The 25 and 36 refer to the size of the lens opposite the eyepiece in mm. The larger the lens the more light it gathers. This of course makes for a heavier monocular and a larger one. I have a 10x25 and it is fine. You have to have a steady hand though in using the devise.
1090076
look for the size of a particular glass in the product description (on Amazon of course). you will see numbers like this 55-18-145 55(mm) will represent the lens width 18(mm) will represent the bridge width 145(mm) will represent the overall length of the arm these 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.
49300
You need to know your glasses prescription. If you're nearsighted, (need correction for distance sight your rx will be a negative number. The lenses come in 0.5 increments. For example I have a -3.75 correction. Since it is in between correction options I ordered a -3.50. (If your in between order the lesser strength). If you are far sighted the correction will be a +.(ie reading glasses). Hope that helps.
2230132
All I know is that it refers to the unit of measurement of the optical power of the lens. I can't quantify the numbers, but this lamp magnifies very well.
77652
Yes, somebody here said +.2 or something like that.It is minor but present; makes screen seem just a little bit bigger.You can get them as prescription lenses if you need more.
1632329
Hi, The focusing distance is always measured from the sensor. Therefore, subtract the distance from the sensor to the front of the lens barrel (approximately 3 inches), and you are left with actual "working distance" of about an inch. Hope that helps.
1253935
After using it, you can inspect it with a magnifier. I saw no problem and continued to use it on my lenses and filters. I'm happy with mine.
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.
377710
I not sure what you mean by 'strength'. I certainly do not have a spectrum analyzer or light meter to measure intensity and wave lengths from a specification perspective. What I can tell you is that I have prior experience with UV light in water supply systems and air vent systems and the results I have achieved with this device are consistent with these other better known systems/applications. Furthermore, like I posted, this is not a toy and should be handled as a tool. I also bought the UV glasses for eye protection, keep my skin out of the light ray, and keep me kids away when in use. One really good indication of it working is the 'ozone' smell associated with disinfected area. It is the same smell you get after a lightning strike. To find out how it works, I would suggest looking into water supply UV light systems. It takes very little exposure to UV light to kill bacteria that can be found in well water. I would be happy to share specific details if know the application for which you are considering this purchase.
336773
Hi, I said I would check the use of the MaxTV glasses with my 4.25 Diopter contact lenses removed.I did, the focus adjustment did NOT go quite far enough to give a sharp focus. It was very close,but not quite there. If you used a two diopter, I don't think you would have a problem, even a 3 diopter would probably work. So for what it's worth. Ang, again, they work as I wanted them to.
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.
438324
These glasses actually do have a magnification of +.25. I actually took them to my eye doctor and they measured the power for me. To put this in perspective, many reading glasses are +1 magnification. +.25 is the smallest increment, incrementing at .5 .75 and 1. So, the magnification is quite small, it just helps things become a little clearer.