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!
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.
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.
1379828
I am just guessing but I assume it is 2 and 1/2 magnification; I have one of these and the cord that you put around your neck can be adjusted to bring your work into focus so I wouldn't worry about it. I love mine! Well worth the money!
1558346
I ordered a pair for myself and 1 pair for each of my sisters in new mexico and texas. We all decided they were not user friendly for us. I don't know the strength but I can tell u this, you cannot see anything unless u hold the item about 1/8th of an inch away from our eyeglasses (we all wear glasses. we were hoping we could get splinters out but we all decided that they would not work for that either. all 3 pairs were thrown in the trash. they just did not work for us. hope this helps u
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.
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.
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.
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.
1591412
This is a very complicated answer. I defer to this link.http://www.astroadventures.net/cohen/articles/Wear%20or%20Not%20to%20Wear%20Glasses.pdfWhether you wear glasses or not, each lens that you use requires that your eye be placed at an optimum distance from the lens. Wearing glasses prohibits one from getting one's eye close enough to enjoy the full field of view with some lenses but not others. The preferred method is to NOT wear glasses and each person must adjust the focus for the best clarity. If your wife has an astigmatism, you can switch to higher eye relief lens while wearing glasses or purchase Televue Dioptrx Astigmatism-Correcting Lenses while not wearing glasses. Have her optometrist make her a monocle. This is a very complicated answer. I defer to this link.http://www.astroadventures.net/cohen/articles/Wear%20or%20Not%20to%20Wear%20Glasses.pdfWhether you wear glasses or not, each lens that you use requires that your eye be placed at an optimum distance from the lens. Wearing glasses prohibits one from getting one's eye close enough to enjoy the full field of view with some lenses but not others. The preferred method is to NOT wear glasses and each person must adjust the focus for the best clarity. If your wife has an astigmatism, you can switch to higher... » Read More This is a very complicated answer. I defer to this link.http://www.astroadventures.net/cohen/articles/Wear%20or%20Not%20to%20Wear%20Glasses.pdfWhether you wear glasses or not, each lens that you use requires that your eye be placed at an optimum distance from the lens. Wearing glasses prohibits one from getting one's eye close enough to enjoy the full field of view with some lenses but not others. The preferred method is to NOT wear glasses and each person must adjust the focus for the best clarity. If your wife has an astigmatism, you can switch to higher eye relief lens while wearing glasses or purchase Televue Dioptrx Astigmatism-Correcting Lenses while not wearing glasses. Have her optometrist make her a monocle. « Show Less
581157
As effective? That depends on what you mean... As effective against eye strain.. No. Period.This is readily confirmed at Gunnar's website:http://www.gunnars.com/view_crystal_lenses.php"The CRySTALLINE lens tint and coating formula is designed specifically for the graphic designer, video/film editor, or creative visual artist that requires an equally balanced color spectrum. If your profession does not allow for a shift towards the warmer part of the color spectrum, with enhanced contrast ie. your tasks require you to design or work in true color, then this lens option is for you. However, if your profession does not require you to perform many daily tasks in true color, then AMBeR is the most effective lens choice." As effective? That depends on what you mean... As effective against eye strain.. No. Period.This is readily confirmed at Gunnar's website:http://www.gunnars.com/view_crystal_lenses.php"The CRySTALLINE lens tint and coating formula is designed specifically for the graphic designer, video/film editor, or creative visual artist that requires an equally balanced color spectrum. If your profession does not allow for a shift towards the warmer part of the color spectrum, with enhanced contrast ie. your tasks require you to design or work in true... » Read More As effective? That depends on what you mean... As effective against eye strain.. No. Period.This is readily confirmed at Gunnar's website:http://www.gunnars.com/view_crystal_lenses.php"The CRySTALLINE lens tint and coating formula is designed specifically for the graphic designer, video/film editor, or creative visual artist that requires an equally balanced color spectrum. If your profession does not allow for a shift towards the warmer part of the color spectrum, with enhanced contrast ie. your tasks require you to design or work in true color, then this lens option is for you. However, if your profession does not require you to perform many daily tasks in true color, then AMBeR is the most effective lens choice." « Show Less
1025376
Sorry, but I don't have an expert answer. Here's what I did. I simply measured, with a very accurate ruler the exact outside center cross distance on the lens. No matter if it measures in inches or metric, just Google the number for a conversion. Worked perfect for me on the first and subsequent orders.. The covers fit perfect, are very well made and I'm very happy to have this protection for all of my lenses. Hope this "grass-roots" method works for you. Bob D., Maine
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
1177291
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
57695
The goggles only come with a negative value which is for near-sighted. Mine were totally useless, terrible distortion, I could not use them and was given bad information by customer service. When I complained, iI was treated rudely. They offered no positive numbers for far-sighted
1749
The numbers 1.25, 1.5 etc refer to the maginification of the lens, the reading glass strength. The frames are all sized the same, for a unisex head shape. The temples are adjustable in length assuring a comfortable fit on a wide variety of head sizes. You'll need to know which power (+2.0? or +1.5? ect) you'll need for the lens of course. Thanks,
294870
When you use it with the little white globe thing, you hold it up against your subject and read the light from there. That's really what this is for. You can also slide the globe out of the way and use it to measure reflected light, but that's going to be fairly inaccurate (since it is hard to point a meter like this with any degree of precision). But still, you point it at your subject, press the button, then look at the reading.