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!
1216096
I have different sizes for different areas. I have been using the 1.0 for my face, 0.5 for around the eyes and 2.0 for body areas. I hope this helps. I actually did my face last night.
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.
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.
187865
I bought these for my husband who normally uses a 2.00 strength. I've borrowed them and can see great (I usually use a 2.50). I don't know what 200 means per the description of the maker--maybe a typo?
1213448
+3.5. And, besides: I tried them in a store and found that they they work superbly for adjusting on the fly between -6 and +3.5 correction (more or less). The optics seem excellent. As a fashion statement a bit awkward but hard to make the double lens system look better. The dial adjusters are discretely positioned and effective. I have no idea about durability.
2071543
I physically measured mine using a digital caliper, it can only hold lenses with diameter 65mm safely.
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.
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.
1677692
I'd say that this is more along the lines of a 'generally specific' more so than a 'literally specific' measurement. I'm sure you can find the right reading given enough time. This uses displacement to gauge the proof of a liquid so you'll have to be sure to let the hydrometer be free from the edges of its container and the water must be completely still. So yes, it will differentiate but you'll have to have a really good eye for it!
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.
882730
When I look through a eo tech with its red dot and circle they are very fuzzy to me. The triangle reticle is sharp with no blur and comes to a nice fine point which I use for aiming. I really don't know how a astigmatism would effect it but for my eyes it's great.
571851
no, it measures the light reaching the subject which is independent of the lens used. It gives you accurate light measurements either in e.v. units, or in f stops. f stops as a measurement of light are equivalent. Differing lenses will affect the depth of field, but the amount of light will be constant and not vary with the lens. Thus, f/1.4 on a 50mm lens will give you the same exposure as it would on a 100mm lens.
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.
847841
Sorry, Heather, I don't know the answer to that question. I was recently using my table saw when a piece of Cedar, about 1"x4" flew off the blade and hit my chest. It hurt like crazy. I was wearing eye-glasses but no goggles - lesson learned. I turned the saw off, vacuumed all the sawdust and didn't use it again until a few days ago when I received the goggles. My ... guess ... is they are osha approved. Hope that helps, and good luck.
625014
Don't use it much anymore. When I did, I tested it and found it doesn't make much diff. The thing is, it's field of view widens as it gets further away. So if you measure something that is very small from a longer distance, you'll get a bad reading. When I used it, I was measuring small packages 5x8 inches from a very close distance like 1-2 ft. Sorry I can't be more help.
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