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!
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.
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.
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.
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!
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!
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.
1747
These numbers refer to the strength (magnification) of the lenses. Higher numbers magnify more.
897742
I have been satisfied with my refractometer so far. I previously had one that came in a gem lab I purchased 25 years ago and it wasnt nearly as easy to read as this one. No complaints to this point.
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.
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.
967887
The magnifying strength is 3x, with a 5x, 1" bubble. I have never figured out how to use it to magnify my cross stitch cloth, only the pattern, which is still a great help.
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 :)
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.
866403
I haven't used it, bought it for a professional guide in Africa. Has a little square in the center to center the target with. Is 6x magnification, if I recall right, so does magnify the target. with that magnification, I'd put 400 yds, in a real steady hold, hand braced on something at 400 yds..maybe a bit less. everything is fog proof these days, and probably water proof,if you're talking rain..don't know about scuba diving with it. you might want to go to the Optics Planet site, as they have the breakdown on those things on their site.
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
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.