Reasonable prices for great glasses

Discussion in 'Glasses' started by squarenesswafer, Jun 4, 2006.

  1. squarenesswafer

    Dr. Leukoma Guest

    This is what I was told by someone who works for Essilor, who is in
    charge of their coating lab here in Dallas. He said that the results
    of their marketing were that preference was shown for the colorized
    product, and so they never marketed the colorless version.

    Believe it, or not.

    DrG
     
    Dr. Leukoma, Jun 6, 2006
    #21
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  2. squarenesswafer

    Dr. Leukoma Guest

    "Colorless" with respect to A/R is most likely a relative term. The
    fact is they can alter the color balance.

    DrG
     
    Dr. Leukoma, Jun 6, 2006
    #22
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  3. squarenesswafer

    LarryDoc Guest

    I'll join in here with a "ditto". Polycarb is best used as a packaging
    material or aircraft window (for which it was originally designed and
    intended), not for ophthalmic lenses except when there is no other
    alternative. I don't think I've dispensed but a handful of polys in the
    last 5 years since Trivex and other high-index, low specific gravity
    materials "matured" into use.

    Shamir's Genesis and Piccolo and Hoya's Trivex PALS are not just
    "premium" in my office, but the "standard of care".

    LB, O.D.
     
    LarryDoc, Jun 8, 2006
    #23
  4. OK I've been bashing poly for a long time, but I must say they
    occasionally have a place in addition to helmet visors and what not.
    For example, a +1.00 or -1.00 where safety and cost are prime factors.
    Esp. if they want dead white (no color) in the lens. The chromabbs will
    be pretty minimal in low Rxs. But I'm for Trivex in most Rxs under 4 D.

    C'mon Hoya, are you listening? Bring on a Trivex version of Tact! Please

    w.stacy, o.d.
     
    William Stacy, Jun 8, 2006
    #24
  5. I'm with mike on this one. There is no colorless AR coating, since they
    all have to select a wavelength or two to reflect, and the reflection
    will have the color(so) of the wavelength that is reflected. For the
    reflected light to be colorless (white), it would have to reflect all
    wavelenghts pretty much equally. The only lens that does that is an
    UNCOATED lens.

    w.stacy, o.d.
     
    William Stacy, Jun 8, 2006
    #25
  6. squarenesswafer

    Dr. Leukoma Guest

    I appears as though I have a choice to believe you or the guy whom I
    have known for many years and who has spent most of his professional
    career developing coatings. I'll have to give this some deep thought.

    DrG
     
    Dr. Leukoma, Jun 8, 2006
    #26
  7. squarenesswafer

    Dick Adams Guest

    (anti-reflective coatings)

    Reflections from the surfaces of my $29 Zenni's have got a
    green-looking dichroic sheen. Reminding very much of
    what one gets from an A-R coating. As these are rimless
    and inexpensive, they must be of polycarbonate. I did not
    request coating.

    Considering what has been said here, one must wonder how
    Zenni could provide A-R coatings in such inexpensive eye
    glasses.

    Well, one thing -- slight blemishes in the coating are beginning
    to show in the coatings around the bridge screws. Possibly the
    glasses will need to be replaced after a year or so.

    Since these are reading glasses, I don't know why they should
    be A-R coated. My question to Zenni would be: could the
    eyeglasses be supplied without the coating. Maybe I should ask
    for my money back on the first pair, since I did not want them
    coated.
     
    Dick Adams, Jun 8, 2006
    #27
  8. squarenesswafer

    Dr. Leukoma Guest

    Stock lenses are available with coating. The better coatings don't
    chip, and will resist scratches. It's a different ball game when the
    lens has to be surfaced, as is the case for higher prescriptions and
    multifocals, and the coating has to be applied afterwards thereby
    diminishing the economy of scale.

    DrG
     
    Dr. Leukoma, Jun 8, 2006
    #28
  9. OK it would be THEORETICALLY possible to construct a multi-layer of 3
    coatings, one for each of the primary color wavelengths, each layer with
    appropriate indices of refractions and thickness appropriate for it's
    substrate (being the underlying lens or the next layer "down" in the
    stack. I do know that no such coatings are commerically available for
    glass or plastic, if they ever existed at all.

    w.stacy, o.d.
     
    William Stacy, Jun 8, 2006
    #29
  10. One more thought. Even if you got a perfect result with the above, most
    ambient light has many wavelengths in addition to those of the primary
    colors. Those wavelengths would be reflected much more strongly than
    those of the primaries, so the resultant reflections would necessarily
    have color. E.g. say at sunset, the orange sunlight would reflect
    orange off the "colorless" coating. Colorless under lab conditions only
    I'm afraid...

    w.stacy, o.d.
     
    William Stacy, Jun 8, 2006
    #30
  11. ladavid_johnson, Jun 11, 2006
    #31
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