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SWARO COATING PROVIDE UV BLOCK/PROTECTION? (1 Viewer)
- Thread starter misccom
- Start date
Alexander Stöhr
Well-known member
Hello Anna,
welcome to birdforum!
I cant answer your question, but I remembered another thread in a german forum, where it was answered. Yes, its in german, but I hope its helpful in times of powerful online translators: Erhöht sich beim Beobachten die Gefahr durch UV-Licht?
The important part is that despite the glass blocks enough of the UV light you should never look into the sun through binocuars.
The answer from the mentioned threads is, that the glass blocks enough of the UV light except when the binocular uses plastic lenses (only found in kids toys)
welcome to birdforum!
I cant answer your question, but I remembered another thread in a german forum, where it was answered. Yes, its in german, but I hope its helpful in times of powerful online translators: Erhöht sich beim Beobachten die Gefahr durch UV-Licht?
The important part is that despite the glass blocks enough of the UV light you should never look into the sun through binocuars.
The answer from the mentioned threads is, that the glass blocks enough of the UV light except when the binocular uses plastic lenses (only found in kids toys)
Last edited:
Thank you Alexander for forwarding this informative and helpful thread. Much appreciated.
Below is the translated information, in the event that others might find it helpful (in English)l:
First of all, you should make sure of the material the lenses of your binoculars are made of. Should it be cheap plastic, you should indeed remain cautious. Plastic lenses are only used in play or fun items as far as I know, but in most cases binoculars contain actual glass lenses and their properties protect you from UV light very well. Because every ordinary glass, and also the optical glass used for binoculars, is largely impermeable to the majority of UV radiation. So you don't need to worry when looking through "real" binoculars. (You don't even need to wear sunglasses to look out through your apartment window.)
UV radiation consists of light of different energies. The energy range of UV light can be roughly divided into three areas, UV-A, -B, and -C, with the energy content increasing from A to C. The medium and high energy areas, i.e. UV-B and -C, are completely blocked by normal glass. From the UV-A range, a small part of the radiation with an intensity of about 10-20% can penetrate, assuming a glass layer of a few millimeters. (For this reason one hardly ever tans behind a window, or at most very slowly, because the UV-A radiation necessary for skin tanning is too weak behind it). However, if the light has to penetrate about 8-10 centimeters of glass on its way through normal binoculars - this thickness comes together in every binocular tube through about 10 lenses and through the thick prismatic glass blocks - there is then almost nothing even from the UV-A radiation more left. For this reason, your eyes are sufficiently protected when looking through binoculars, an additional UV filter is not necessary. Compared to the unprotected eye, observing with binoculars therefore means effective protection against UV light!
There are other reasons why most sunglasses, in contrast to binoculars, have additional UV protection for the "glasses". On the one hand, the panes are mostly made of plastic, and this is not only very thin, but in contrast to glass, it is also much more permeable to UV light if it is not provided with special additives. On the other hand, the dark tint of the panes opens their pupils wider, which means that more UV radiation gets into the eye if it could enter unfiltered. Bad sunglasses with UV-permeable and only tinted plastic lenses will therefore damage your eyes, but even with the worst-looking cheap binoculars you will protect them (if they are not plastic toys) thanks to their thick glass layer.
If you should have concerns about the magnifying effect of binoculars, that this also gives rise to fear of an increased effect of the light, Mr. Schön has already explained to you that this is not the case. Magnification does not increase the amount of light that reaches your eye through the binoculars. You can easily understand this as follows:
Suppose you are watching your child without binoculars, but through a tube long enough to have a passage just big enough for you to see your child fully inside. The amount of light that now falls through the tube into your eye is only dependent on the passage of the tube. If you now put a few skilfully combined lenses and prisms in this tube, then due to the absorption of the glass, more than 90% of the original amount of light still arrives with good binoculars, but by no means the former 100% light with the tube without lenses. This incoming amount of light is now simply "better distributed" by the optics in your tube, i.e. spread apart in a quasi-enlarging manner, so that you see a larger image. However, this larger image is made from the same amount of light as the unenlarged image.
If you look through a tube or through binoculars, all light that would otherwise come from the environment with the naked eye is blocked out. This hidden part is quite significant when you realize how small the picture area of your child is compared to the total area of your natural field of vision. This masking also reduces the radiation damage to your eyes considerably.
Below is the translated information, in the event that others might find it helpful (in English)l:
First of all, you should make sure of the material the lenses of your binoculars are made of. Should it be cheap plastic, you should indeed remain cautious. Plastic lenses are only used in play or fun items as far as I know, but in most cases binoculars contain actual glass lenses and their properties protect you from UV light very well. Because every ordinary glass, and also the optical glass used for binoculars, is largely impermeable to the majority of UV radiation. So you don't need to worry when looking through "real" binoculars. (You don't even need to wear sunglasses to look out through your apartment window.)
UV radiation consists of light of different energies. The energy range of UV light can be roughly divided into three areas, UV-A, -B, and -C, with the energy content increasing from A to C. The medium and high energy areas, i.e. UV-B and -C, are completely blocked by normal glass. From the UV-A range, a small part of the radiation with an intensity of about 10-20% can penetrate, assuming a glass layer of a few millimeters. (For this reason one hardly ever tans behind a window, or at most very slowly, because the UV-A radiation necessary for skin tanning is too weak behind it). However, if the light has to penetrate about 8-10 centimeters of glass on its way through normal binoculars - this thickness comes together in every binocular tube through about 10 lenses and through the thick prismatic glass blocks - there is then almost nothing even from the UV-A radiation more left. For this reason, your eyes are sufficiently protected when looking through binoculars, an additional UV filter is not necessary. Compared to the unprotected eye, observing with binoculars therefore means effective protection against UV light!
There are other reasons why most sunglasses, in contrast to binoculars, have additional UV protection for the "glasses". On the one hand, the panes are mostly made of plastic, and this is not only very thin, but in contrast to glass, it is also much more permeable to UV light if it is not provided with special additives. On the other hand, the dark tint of the panes opens their pupils wider, which means that more UV radiation gets into the eye if it could enter unfiltered. Bad sunglasses with UV-permeable and only tinted plastic lenses will therefore damage your eyes, but even with the worst-looking cheap binoculars you will protect them (if they are not plastic toys) thanks to their thick glass layer.
If you should have concerns about the magnifying effect of binoculars, that this also gives rise to fear of an increased effect of the light, Mr. Schön has already explained to you that this is not the case. Magnification does not increase the amount of light that reaches your eye through the binoculars. You can easily understand this as follows:
Suppose you are watching your child without binoculars, but through a tube long enough to have a passage just big enough for you to see your child fully inside. The amount of light that now falls through the tube into your eye is only dependent on the passage of the tube. If you now put a few skilfully combined lenses and prisms in this tube, then due to the absorption of the glass, more than 90% of the original amount of light still arrives with good binoculars, but by no means the former 100% light with the tube without lenses. This incoming amount of light is now simply "better distributed" by the optics in your tube, i.e. spread apart in a quasi-enlarging manner, so that you see a larger image. However, this larger image is made from the same amount of light as the unenlarged image.
If you look through a tube or through binoculars, all light that would otherwise come from the environment with the naked eye is blocked out. This hidden part is quite significant when you realize how small the picture area of your child is compared to the total area of your natural field of vision. This masking also reduces the radiation damage to your eyes considerably.
Just wanted to say welcome to BirdForum from all the staff and moderators. Looks like Alexander has stepped up with answer. Great scope btw.
Rich
Rich
A look at any of the transmission tests of binoculars perfomed by "allbinos" or by Gjs van Ginkel in his "House of Outdoor" tests will show that there is always a rapid fall in transmission below 400nm.
Plastics are often maligned, but the materials used for spectacle lenses have much better UV absorption than opthalmic crown glass, which transmits 21% UVB and 80% UVA. Most of them such as Trivex and polycarbonate completely block UVA and UVB.
I would nevertheless echo Alexander's advice never to look at the sun. The filter I use for occasional sunspot observation with my scope has 99,999% absorption.
John
Plastics are often maligned, but the materials used for spectacle lenses have much better UV absorption than opthalmic crown glass, which transmits 21% UVB and 80% UVA. Most of them such as Trivex and polycarbonate completely block UVA and UVB.
I would nevertheless echo Alexander's advice never to look at the sun. The filter I use for occasional sunspot observation with my scope has 99,999% absorption.
John
Thank you all for the warm welcome to Birdforum and this helpful feedback!
I'll definitely avoid looking at the sun via my scope.
Great to know that optical glass is largely impermeable to UV light. I had been concerned about the exposure (to the eye) of UV light reflected from the ocean, while observing/monitoring seabirds and shorebirds through the scope.
I'll definitely avoid looking at the sun via my scope.
Great to know that optical glass is largely impermeable to UV light. I had been concerned about the exposure (to the eye) of UV light reflected from the ocean, while observing/monitoring seabirds and shorebirds through the scope.
Hi,
first of all, welcome to BF!
If you actually want to observe the day star with your spotter in white light (mainly for sunspots, filaments and granules), Baader AstroSolar 5.0 foil for visual observation in front of the objective is a high quality and safe solution, just make very sure that it cannot be torn away by a gust of wind.
Joachim
first of all, welcome to BF!
If you actually want to observe the day star with your spotter in white light (mainly for sunspots, filaments and granules), Baader AstroSolar 5.0 foil for visual observation in front of the objective is a high quality and safe solution, just make very sure that it cannot be torn away by a gust of wind.
Joachim