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.
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.
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.
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.
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
1211051
What I did was, using a set of metric vernier calipers measure the outside diameter of bothe the Ocular lens (eyepiece) and the objective lens. Then using the Butler creek measurement table, chose the size as close too or slightly smaller than that measurement. I too had issues with finding what I needed and I did have to surf about a bit, but I finally found a table that had all of scope cap sizes and measurements. Hope this helps
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.
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.
47633
So you have the option to have a different strength for each eye? I did not when getting swim goggles and went with something in the middle, so in your case, either 2 or 2.5. I have one eye too strong, one not enough, but that does not seem to be a problem.
49300
You need to know your glasses prescription. If you're nearsighted, (need correction for distance sight your rx will be a negative number. The lenses come in 0.5 increments. For example I have a -3.75 correction. Since it is in between correction options I ordered a -3.50. (If your in between order the lesser strength). If you are far sighted the correction will be a +.(ie reading glasses). Hope that helps.
1922935
Yes - this pair allows for diopter adjustments, which you calibrate when you first use them out of the box (it may make focusing difficult for other eyes than your own, like when you lend your binos to someone else). I think the paperwork included has directions, and if not you can google how to do it :)
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?
21263
i would get the -3 that way you don't cause disorientation, because water as is does have refraction, so i would go with the lowest diopter.
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.
1753205
Thanks for taking the time to reply. I suspected as much, so I have just been using one at a time. Nice to know that I needed to, and should continue to, in the wide angle range.
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.
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.