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!
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
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.
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.
498047
Contact Splaqua. I have a smaller deviation in my correction , and in this situation it is suggested to go with the lower number. I know that Splaqua, and probably others, will help with getting the proper correction for each eye in circumstances that call for it.
82129
I think -4.0 and -4 are the same. If you are near-sighted, you should choose negative.
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 :)
2263148
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 &#9726;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 :)
967886
The magnifier is 5X strength, with a small, stronger bubble. This magnifier is much stronger than the one on my first Ottlite, which was 3X. Also, this one has no rim to interfere with clear views, as did the previous clip-on magnifiers from Ottlite!
814584
Hey you properly calibrated it by using RODI water. You must put RODI water where you use it for the saltwater then just above it is a black cap an under the cap is a screw to calibrate it. So look into the eye part then adjust it to zero then it should work fine
2071543
I physically measured mine using a digital caliper, it can only hold lenses with diameter 65mm safely.
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
1238980
The equation for the volume of a sphere is: V=4/3 &#960;r^3 (that weird n should be "pie" as in 3.14159) Thus, the volume of a 60-inch in diameter (30-inch radius) sphere is as follows: V=4/3 &#960;&#12310;(30 in)&#12311;^3((&#12310;2.54 cm)&#12311;^3)/&#12310;(1 inch)&#12311;^3 (1 mL)/&#12310;(1 cm)&#12311;^3 (1 L)/(1000 mL)=1853 Liters But, the volume of the balloon will depend on the pressure required to fill the balloon because the recoil force of the balloon will increase as the diameter increases. Basically, the pressure inside the balloon will be much higher than the surrounding air pressure. And the balloon pressure will increase significantly as the balloon diameter increases and approaches its burst pressure. So, the equation will be: (P1 (at sea level))/(P2 (needed to fill the balloon) )=V2/(V1(at sea level)) I work with angioplasty balloons (those used to treat blood vessel narrowings) daily and the burst pressure in those balloons is between 8 and 25 atmospheres for compliant and non-compliant balloons. This balloon is a compliant balloon (meaning that it changes shape with various pressures), so I would guess that the burst pressure is less than 8 atmospheres - probably more like 4 atmospheres. Thus: Volume =(4 atm)/(1 atm) x 1853 L=7,400 Liters (at atmospheric pressure) But, no fear, you don't have to fill the balloons to full capacity. By filling the balloons to only 40 inches in diameter, the volume and pressure will be substantially less. By my calculations, only 1100 Liters. As far as this information, you know what they say about experts: They know more and more about less and less until they know everything about nothing.
187867
I also noticed the "200" and assumed that it meant 2.00. Turns out that it did: the glasses are indeed a +2.0 correction. I'm not sure whether they just left out the decimal point after the 2, or maybe "200" is just what they call it.
1990075
you will notice the top of the clear ring starts lined up with zero at the top of the scale. You want to use the top of the ring to get your measurement from. You have to slide the ring back up for each measure. You should measure 3 times or more and average the reads. For a pistol hold the gun down on a table or sturdy surface as just holding it in your hand introduces errors. I found doing that usually caused it to read as much as a pound more than when the guns held butt down on my bench.
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.
1576951
There was no strength specified in the description. After the order was placed, the vendor emailed me to check whether I wanted strength 2.0 (he said that is what I ordered even though I was not able to specify a strength at time of order). That gave me the opportunity to let him know that I wanted 1.75 and that is what they sent. BTW, we love the glasses because it is the small compact size my husband was looking for.