Photochromic lenses and visors

Verdigris wrote:
> Will photochromic lenses work behind a normal visor? I was
> considering getting some but my optician informs me they don't work
> very well inside cars and might well have similar problems in a
> helmet.

If I'm remembering my physics correctly, glass absorbs UV light, but most
plastics don't (at least not so much). So if the lenses are reacting to UV,
they should work better through a plastic visor than a glass windscreen.

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 >> Stay informed about: Photochromic lenses and visors 

"Monkey" <monkey RemoveThis @surfR3M0VEbum.freeserve.co.uk> wrote in message
news:JNidnSVSiIPvc7bYnZ2dnUVZ8t2dnZ2d@brightview.com...
> Verdigris wrote:
>> Will photochromic lenses work behind a normal visor? I was
>> considering getting some but my optician informs me they don't work
>> very well inside cars and might well have similar problems in a
>> helmet.
>
> If I'm remembering my physics correctly, glass absorbs UV light, but most
> plastics don't (at least not so much). So if the lenses are reacting to
> UV, they should work better through a plastic visor than a glass
> windscreen.

Windscreens have a plastic layer between the two glass panes though.


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 >> Stay informed about: Photochromic lenses and visors 

This message is not archived
 >> Stay informed about: Photochromic lenses and visors 

Verdigris wrote:

> Will photochromic lenses work behind a normal visor? I was considering
> getting some but my optician informs me they don't work very well inside
> cars and might well have similar problems in a helmet.

Mine work as well in a helmet as they do outside.
It seems to be impossible to get photochromic lenses that go dark enough.
My first pair, in 1979, was OK but there are just pale imitations nowadays.

--
Eiron

No good deed ever goes unpunished.
 >> Stay informed about: Photochromic lenses and visors 

Verdigris wrote:
> Will photochromic lenses work behind a normal visor? I was considering
> getting some but my optician informs me they don't work very well inside
> cars and might well have similar problems in a helmet.

Works ok for me, but iirc correctly photochromic stuff works on uv, so
if your visor has a uv filter, you're a bit buggered.

Bloody uncomfortable wearing glass under lids.
 >> Stay informed about: Photochromic lenses and visors 

On Tue, 10 Oct 2006 21:03:58 +0200, Tosspot <FrankDotLeake.DeleteThis@esa.int>
wrote:

>Verdigris wrote:
>> Will photochromic lenses work behind a normal visor? I was considering
>> getting some but my optician informs me they don't work very well inside
>> cars and might well have similar problems in a helmet.
>
>Works ok for me, but iirc correctly photochromic stuff works on uv, so
>if your visor has a uv filter, you're a bit buggered.
>
>Bloody uncomfortable wearing glass under lids.

IYHO.
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 >> Stay informed about: Photochromic lenses and visors 

Verdigris wrote:
> Will photochromic lenses work behind a normal visor? I was considering
> getting some but my optician informs me they don't work very well inside
> cars and might well have similar problems in a helmet.
>

Mine work in both the car and the lid.

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 >> Stay informed about: Photochromic lenses and visors 

mb wrote:
> Monkey wrote:

>> If I'm remembering my physics correctly, glass absorbs UV light, but
>> most plastics don't (at least not so much). So if the lenses are
>> reacting to UV, they should work better through a plastic visor than
>> a glass windscreen.
>
>
> Don't know how you work that out, eg:
> http://www.ppeshack.com/glasses/glasses_index.php
>
> Polycarbonate lenses, 99.9% UV Protection.

And you think that UV protection is purely down to the fact it's made from
polycarbonate, do you?

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ZX6R F2 - The Gravelseeker
BOTAFOT #121, BBB #2
 >> Stay informed about: Photochromic lenses and visors 

This message is not archived
 >> Stay informed about: Photochromic lenses and visors 

mb wrote:
> Monkey wrote:
>
>> mb wrote:
>>> Monkey wrote:
>>
>>>> If I'm remembering my physics correctly, glass absorbs UV light,
>>>> but most plastics don't (at least not so much). So if the lenses
>>>> are reacting to UV, they should work better through a plastic
>>>> visor than a glass windscreen.
>>>
>>>
>>> Don't know how you work that out, eg:
>>> http://www.ppeshack.com/glasses/glasses_index.php
>>>
>>> Polycarbonate lenses, 99.9% UV Protection.
>>
>> And you think that UV protection is purely down to the fact it's made
>> from polycarbonate, do you?
>
>
> Eh?
> You said most plastics don't absorb (much) UV. I gave you an example
> of a plastic which, apparently, does.
>
> Ergo, I'm right, you're wrong. Hurrah.

No - I'm right in saying that *if I remember my physics correctly* glass
absorbs UV light,
but most plastics don't (at least not so much).

Evidently I don't remember correctly. My statement's still right though. And
polycarbonate isn't 'most plastics', so you're wrong. Nerr nerr ne nerr
nerr.

Anyway - I've done my research now, and it turns out that it's glass that
absorbs the least UV. Most plastics are not 100% UV resistant, and require a
coating to make them so. Polycarbonate is inherently 100% UV resistant
without treatment. This is a good summary:
http://www.eyetopics.com/articles/33/1/Sunglass-Lens-Materials-and-Coatings

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ZX6R F2 - The Gravelseeker
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 >> Stay informed about: Photochromic lenses and visors 

On Tue, 10 Oct 2006 20:41:28 +0100, Eiron wrote:

> Verdigris wrote:
>
>> Will photochromic lenses work behind a normal visor? I was considering
>> getting some but my optician informs me they don't work very well inside
>> cars and might well have similar problems in a helmet.
>
> Mine work as well in a helmet as they do outside.

OK; thanks.

> It seems to be impossible to get photochromic lenses that go dark enough.

That's always been my main objection.

He did show me some nice frames with magnetic clip-on sunglasses, which
looked quite good. A bit pricy, though, compared to the tat I usually buy.

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 >> Stay informed about: Photochromic lenses and visors 

On Tue, 10 Oct 2006 15:40:14 -0500, "mb" <zierikzeeNO RemoveThis @SPAMgmail.com>
wrote:

>Monkey wrote:
>
>> mb wrote:
>> > Monkey wrote:
>>
>> > > If I'm remembering my physics correctly, glass absorbs UV light,
>> > > but most plastics don't (at least not so much). So if the lenses
>> > > are reacting to UV, they should work better through a plastic
>> > > visor than a glass windscreen.
>> >
>> >
>> > Don't know how you work that out, eg:
>> > http://www.ppeshack.com/glasses/glasses_index.php
>> >
>> > Polycarbonate lenses, 99.9% UV Protection.
>>
>> And you think that UV protection is purely down to the fact it's made
>> from polycarbonate, do you?
>
>
>Eh?
>You said most plastics don't absorb (much) UV. I gave you an example of
>a plastic which, apparently, does.
>
>Ergo, I'm right, you're wrong. Hurrah.

I'd put the champagne down if I were you. Pesky little word, "most",
isn't it.
--
Champ

ZX10R
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My advice as your attorney is to buy a motorcycle
 >> Stay informed about: Photochromic lenses and visors 

Verdigris wrote:
> Will photochromic lenses work behind a normal visor? I was considering
> getting some but my optician informs me they don't work very well inside
> cars and might well have similar problems in a helmet.

Mine do. As long as your visor doesn't block UV, you'll be fine.

Probably.

--
Dnc
 >> Stay informed about: Photochromic lenses and visors