On 12/21/06 11:47 AM, in article
xyBih.12033$Gw4.828@newssvr23.news.prodigy.net, "William Stacy"
<wstacy@obase.net> wrote:

Unfortunately, there are many divergences generated among disciplines that
confuse people trying to understand other specialists in related fields. For
example, the way the direction of polarization was once arbitrarily assigned
was in terms of the direction of the magnetic field in the propagating wave.
Later, it was found that interaction with matter was primarily with the
electric field. The term direction of vibration was then used to replace
direction of polarization. Nevertheless, confusion is still there.

I used the term dielectric because metals do not have a (real) Brewster
angle. That is, simple metallic reflection does not discriminate with
polarization state. That is, polarized glasses could help with sun glare off
of the rust on steel plates put in the roadway, but not the reflection from
clean shiny steel.

Flare is a term used by photographers. It corresponds to the general loss of
contrast from scattered light. It also refers to various artifacts in
photographs that often come from unwanted and often unrecognizable images
generated by specular reflection off of lens surfaces.

Bill
-- Fermez le Bush

Right. This sci.med.VISION, where we use ophthalmic optics terminology,
not precision camera or instrument terminology.  But I still think you
are using the term glare incorrectly even in that context (see my
definition below). And I don't know why you are specifying dielectric
below.  What has that got to do with anything?  Reflected sunlight off
any relatively smooth surface anywhere near Brewster's angle will of
course be polarized, including glass, water, even the atmosphere, which
is why polarized filters are used under those conditions.  We do not use
the term flare in the eye business, except in the context of warning
people not to try to observe the solar variety, and to use protective
eyewear when handling the boating or highway hazard varieties. Your use
of the term here is showing your, er, obfuscatory flair.

w.stacy, o.d.

On 12/21/06 9:04 AM, in article
78zih.35837$wP1.2987@newssvr14.news.prodigy.net, "William Stacy"
<wstacy@obase.net> wrote:

Again, there is terminology confusion. I take glare to be s (senkrecht)
polarized light reflected off of dielectric surfaces, like asphalt, that can
be partially blocked (totally at the Brewster angle) by viewing through
properly oriented polarized film.

Flare is the recording or perception of artifacts in a photograph arising
from light reflected at the surfaces of lens elements.

Bill
-- Fermez le Bush

There you go again.  Please don't use confusing terms like glare and
flare.  Glare refers to distracting light coming from around the object
of regard, and cannot be corrected with any eyeglasses.  Specular
reflection refers to light that is reflected off a relatively smooth
surface like a highway, water and computer monitor or eyeglass lenses.  
These the first two can be fixed with polarized lenses, the second by
the use of anti-reflection coatings.  Let's keep the terminology
straight.  In the present case, if he chooses high index lenses, which
have significantly higher relflectivity, approaching 10%,
anti-reflection coatings will definitely help.  High quality ones (over
$60) are quite durable and always come with guarantees.

w.stacy, o.d.

On 12/20/06 8:06 PM, in article
1166674018.469403.141480@48g2000cwx.googlegroups.com, "midwest_46@yahoo.com"

Antiglare lenses have a polarized coating on them that ideally cuts out a
bit more than half of the light. In addition, it cuts out some reflected
light off of the pavement near what is the Brewster angle. Look that up in
Wikipedia. I personally use CHEAP clip-on polarized glasses for that
purpose.

Antireflection coatings on glasses are nice but usually not durable. They
are anti-FLARE as opposed to anti-GLARE. That is, the typically 4% of light
at a lens air surface is reduced to about 1%. This lets more light get
through and reduces the multiple reflections that might be annoying.

I find antireflection coatings to be more useful in cameras where the stray
light can leave a permanent reminder on the picture. For spectacles, you can
often, but not always, move your head in a way to minimize the annoyance.

-- Fermez le Bush

Hello. I am a 33-year-old male.

I need to get a pair of glasses with the prescription -5.00, -5.00 for
driving, watching movies in a theater, etc. Would it be useful to buy
lenses that have anti-glare or anti-reflective coating on them?

What exactly does this coating do?

Also, I may buy another pair of glasses to use as reading glasses.
These glasses would be used for reading, computer use, etc. Would
anti-glare or anti-reflective coating be useful for these glasses?

I have had driving glasses and reading glasses before, and I don't
think I've ever had anti-glare coating before. I'm not sure, but I
don't think that not having this coating has been a problem.

The coating can cost as much as an extra $75 for each pair of glasses.
So, is the coating worth the price?

Thanks for any information.

John