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red
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Joined: 13 Aug 2007
Posts: 2734
Location: Utah, USA . . . . . . . . . . . . . Sol III
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 Posted: Thu Dec 11, 2008 7:58 pm Post subject: Polarized sunglasses |
 #1 |
| hiflioz wrote: |
Hi Robert,
Robert, how clear are the windlines on the water at Stanwell? We use them a lot to identify wind direction (and approaching wind changes) here in SA, but there are certain days, especially at Myponga, when sunglare makes it impossible to see them. And if you're flying in very light winds <10kts, they don't really show either (I remember flying at Rainbow and finding it very difficult to see them). |
Helen,
You can cut down or eliminate sun glare on water with polarized glasses. You can see clouds and weather differently, also.
The glare of light reflected from water (or a cloud) is polarized light.
One caution: Cheap sunglasses may not block all UltraViolet light (UVA and UVB). These are far worse than no sunglasses
at all, and may be illegal in some countries (as they are in Oz).
Another consideration: LCD readouts are polarized, so LCD varios and digital watches may be difficult or impossible to read,
with polarized glasses.
If you can see light though two "stacked" lenses (holding two identical pairs of sunglasses, one above the other), then
rotate one lens 90 degrees. If the "stacked" lenses get darker or lighter, they are polarized. Well-polarized lenses will
go fully black, when the stacked lenses are rotated to the "right" position. If you look at the glare from water through a
polarized lens, and rotate the lens as you do, you will see the glare get dimmer, at a certain angle. If the sunglasses
are well-made, the sunglasses will be horizontal (as you would wear them) when the glare is dimmest.
_________________
Cheers,
........Red.........................
Pssst! New pilot? Free advice, maybe worth the price,
http://www.xmission.com/~red/
H4, Moyes X2, Falcon Tandem, HES Tracer, Quantum |
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hiflioz
3 thumbs up
Joined: 27 Jul 2008
Posts: 826
Location: south australia
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| Posted: Thu Dec 11, 2008 8:25 pm Post subject: Re: Polarized sunglasses |
#2 |
| red wrote: |
| hiflioz wrote: |
Hi Robert,
Robert, how clear are the windlines on the water at Stanwell? We use them a lot to identify wind direction (and approaching wind changes) here in SA, but there are certain days, especially at Myponga, when sunglare makes it impossible to see them. And if you're flying in very light winds <10kts, they don't really show either (I remember flying at Rainbow and finding it very difficult to see them). |
Helen,
You can cut down or eliminate sun glare on water with polarized glasses. You can see clouds and weather differently, also.
The glare of light reflected from water (or a cloud) is polarized light.
One caution: Cheap sunglasses may not block all UltraViolet light (UVA and UVB). These are far worse than no sunglasses
at all, and may be illegal in some countries (as they are in Oz).
Another consideration: LCD readouts are polarized, so LCD varios and digital watches may be difficult or impossible to read,
with polarized glasses.
If you can see light though two "stacked" lenses (holding two identical pairs of sunglasses, one above the other), then
rotate one lens 90 degrees. If the "stacked" lenses get darker or lighter, they are polarized. Well-polarized lenses will
go fully black, when the stacked lenses are rotated to the "right" position. If you look at the glare from water through a
polarized lens, and rotate the lens as you do, you will see the glare get dimmer, at a certain angle. If the sunglasses
are well-made, the sunglasses will be horizontal (as you would wear them) when the glare is dimmest. |
Yes, you're quite right, Red. My hubby and I both wear light brown *prescription* polarised lenses. The colour increases contrast and after I put them on for the first time a few years ago I knew I'd never fly with ordinary (untinted) prescription lenses again. The situation at Myponga is unusual because the specs don't help. Usually, it's mid-late afternoon when the sky and sea look silver (there's some cloud cover) slightly to the north.
I'd add that for my latest set of lenses I went to a local optometrist rather than the "fast food" version of franchise spectacle makers. Those lenses were higher quality yet again - the optics are amazing (instantly noticeable when I put them on). Pilots who wear prescription specs, it really is worth paying the extra money for quality polarised lenses. Choosing the non-reflective coating makes them smudge easily but it also improves vision in many situations.
_________________
Cheers from Down Under
Helen
Falcon1 170, Fun 190, Malibu 188, Malibu 166, Shark 144, Litesport3, Adv, GT, SO |
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