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!
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.
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.
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.
1165242
Wow, that answer isnt listed ANYWHERE, not even their website. This sight is identical in width to the one I just took off, that was a .100, so it appears to be just a standard general width sight.
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
1190630
More strength? If you could explain I might be able to answer. This is a standard adapter for your camera-specific T-ring. You need both to mount/use a camera with a telescope (unless you get real lucky shooting through an eyepiece) - I've used them with heavy film cameras with no problem - on a decent telescope. If the 'scope is lightweight it's probably not good for astrophotography anyway. But the "strength" issue is unclear - are you planning on some other kind of use?
4681
Actually I am not aware of anywhere online that shows measurement. I use the eye dropper bottle that comes with the order and basically do the math myself.I always drink a full glass or cup of distilled water whether I am adding adding 3 drops or 23 drops.
282298
I do not know what 'cyl' and 'axis' measurements are, but, here is what we did:1. when ordering Speedo goggles, we got the +/- number, from our opthomologist.2. when ordering the ProMate snorkeling mask, we selected the the color and then selected the appropriate eye-adjustment (my son is nearsighted) from the "size" pull-down menu on the ProMate scuba options.3. My 13 year-old son loves the mask and was our family underwater photographer in Cozumel.
349530
It does refer to the diameter of your lens, if you are unsure or want to double check, look on the inside of your lens cap!
1515978
I have found no differences between the different diffraction glasses that I have purchased from Amazon. I have been buying large quantities for a couple years now to pass out to 8th grade science students in an Expanding Your Horizons project that I volunteered for. We use them to describe how Optical Emission Spectroscopy works in our lecture called "Chemistry of Light" I have never even tried them under black light, but will look into that for future reference. Not sure about the actual diffraction grating sizes being used but we are just looking to get the children's interest sparked so we haven't been very scientific about it. I have found no differences between the different diffraction glasses that I have purchased from Amazon. I have been buying large quantities for a couple years now to pass out to 8th grade science students in an Expanding Your Horizons project that I volunteered for. We use them to describe how Optical Emission Spectroscopy works in our lecture called "Chemistry of Light" I have never even tried them under black light, but will look into that for future reference. Not sure about the actual diffraction grating sizes being used but we are just looking to get the children's interest... » Read More I have found no differences between the different diffraction glasses that I have purchased from Amazon. I have been buying large quantities for a couple years now to pass out to 8th grade science students in an Expanding Your Horizons project that I volunteered for. We use them to describe how Optical Emission Spectroscopy works in our lecture called "Chemistry of Light" I have never even tried them under black light, but will look into that for future reference. Not sure about the actual diffraction grating sizes being used but we are just looking to get the children's interest sparked so we haven't been very scientific about it. « Show Less
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.
1190631
As per previous answer it is just standard adapter for a camera specific T ring so you can attach camera to telescope that has 1.25 eyepiece It will not give more "strength" (I assume you mean magnification).
1660679
As others have stated there is no magnification. The 1-4 I believe refers to the MOA size of the dot. 1 MOA for more precise aiming 4 MOA for faster sight aquisition. You probably already know this but 1 MOA is roughly equal to 1 inch at 100 yards, 4 MOA roughly 4 inches so the bigger the dot the more of your target is covered and the less precise your aiming. This is a very generalized explanation. Hope it is helpful.
1951961
There are three lenses which can be stacked for greater magnification. Using the first lens only it's about 8-8.5 inches. Add the second lens and that drops to about 4 - 4.5 inches. Add the circular lens (for the right eye only) and it drops to about 3/4 - 1 inch. Hope this helps.
21264
Honestly there isn't a big deal between -3.50 and -3.00 and you can get either one and you will see grate. But if you are still not satisfied go for 2 pairs of one -3.00 and -3.50 and just switch lenses and this way you have to pairs with perfect match
1714253
That is correct the aperture is 100mm. The first set of numbers [22-67x] indicates the magnification capability of the optic. On the other hand the second [100] indicates the aperture if I'm not mistaken.