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.
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
234982
Pardon my terseness, but the answer to this question is clear from the product description. Only two measurements define a cylinder (length and diameter). The product advertises a 3.5" diameter and telescopes to over 36" in length. If your measurements are accurate - then it fits.
1645861
Paul, thank you. From the specs alone, I agree, but I think there must be some significant difference between the two sets. The only thing I can see from the specs is something about the eyepiece adjustment.
868633
My understanding is that it just has to be in your field of view (the instructions in the box say as much). I am not a doctor.Don't forget the inverse square law, though; in other words, the farther away from the light you are, the less light energy you'll receive (duh)... but double distance is 1/4 power, triple distance, 1/9 etc. I think it's designed to be at about arms-length, give or take, not like 10'.
290031
If I measured correctly it's 1.5 inches. Like I said I'm still trying to learn how to use it. I haven't had much experience with optics
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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
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
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.
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.
1640292
I guess you didn't have the link http://www.amazon.com/Vortex-Solo-10x36-mm-Monocular/dp/B00161ZI4A/ref=cm_cd_al_qh_dp_t Specs: Eye relief: 15 mm; Exit pupil: 3.6 mm; Linear F.O.V: 325 feet @ 1,000 yards; Angular F.O.V.: 6.2 degrees; Close focus: 16.4'; Length: 4.9"; Weight: 9.7 ozs.
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.
614136
Some people with an astigmatism will see more than one dot or the dot will seem out of round. I am one of those people and you just get use to it over time. My aimpont and delta point do the same thing.
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.
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.
1198219
Your lens should say what distance it is accross the lens (diameter) or you can measure it.
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.