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...
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.
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
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
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.
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.
2259983
I have found it only to be a slight adjustment. If you take it off the camera then move it in front of something close to focus on. Adjust the ring and you will see a slight difference. Personally I don't use the diopter after initial focus.
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.
82129
I think -4.0 and -4 are the same. If you are near-sighted, you should choose negative.
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
98633
Its actually not bad. I sighted in at 25yds and at 50yds. At 50 it was a little faint but you could definitely see it.. make sure you're not using a bright white paper to sight though as it will wash out. I really wasnt even expecting that for the price. It's worth the 12 bucks.
109311
I am actually hesitant to answer this question, because obviously no one here read the product description. On the first line it states "8 1/2-10 1/2" eye relief". So 10.5" at 2x, and 8.5" at 7x.
727222
The CPC is listed as using 1.25" star diagonal. You should be able to use the 2" star diagonal in this kit to use the eyepieces in this kit. You will need to remove the 2" diagonal and reattach your 1.25" diagonal to use your 1.25" eyepieces.
1340325
The first number is the power of the lens, that is how much it will magnify the image. The second number represents the diameter of the lens in mm. They work together to calculate a number called the "exit pupil" or "exit ratio". Take the lens size and divide it by the power to get this number. The higher the number, the brighter the image. For example, 10x50 will give an exit ratio of 5.0, 8x42 would be 5.25, 10x42 would be 4.2. In my opinion, the exit ratio is more important than the power. My favorite binoculars are 8x50 (6.25) but I also just bought 10x50 as a gift who is delighted with that configuration. Stay away from high-power binoculars. They, for me, are too hard to keep steady due to the high magnification. I hope this helps. -Norm
1098705
I also see an oblong dot, almost a set of dots that seem not round. I was diagnosed a few years back with a "mild astigmatism", and although I do have glasses, I generally do not wear them. I was unsure if it was the astigmatism or a faulty unit, so spoke with Trijicon on the phone and they said to exchange the unit with a new one. I did so through Amazon and found that the new unit did the exact same thing. I believe that its the astigmatism, and although mine is so mild that I don't have the need to wear glasses, it still makes the laser dot seem oblong.
676547
I don't know how to measure parallax, but at 25-30 yards, parallax is not a problem. I have excellent clarity throughout zoom range. Worth the money!
2173896
Not at all. From the description, it is supposed to help people with imperfect vision. I found it pretty useless as I have 20/20. It further seemed like I was looking down a paper towel roll. I am very interested in their other magnifier which can work with a variety of others. Primary Arms makes one but I haven't seen any side by side comparisons.