Nikon 1 lenses. Glass or Plastic?

Discussion in 'Digital Photography' started by Bob AZ, Aug 15, 2012.

  1. Bob  AZ

    Bob AZ Guest

    Are the lenses for the new Nikon 1 cameras "glass or plastic"?

    Bob AZ
    Bob AZ, Aug 15, 2012
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  2. Bob  AZ

    Me Guest

    I had a quick look at Nikon's site, there's no definitive answer there,
    but some diagrams showing aspherical elements in the wide angle zooms,
    some ED (glass) elements, some simple elements which are probably glass.
    Nikon mention some "high refractive index" elements, which makes me
    wonder if they could be plastic.
    The aspherical elements are possibly "hybrid", with an aspherical shaped
    plastic lens laminated to a glass lens. These are pretty normal on even
    professional level 35mm format ultra-wide zooms. Cost for ground glass
    aspherical elements is very high, Nikon has their "PGM" process for
    moulding glass as used in the 14-24mm zoom, but I doubt they use this in
    slower consumer lenses like the 1 series.
    Hmmm - that's a long winded answer, short answer is probably glass /and/
    plastic in the wide zooms, probably just glass in the longer lenses -
    unless they've got the unspecified composition high refractive index
    elements in them - and those are plastic.
    Does it really matter?
    Me, Aug 15, 2012
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  3. Bob  AZ

    David Taylor Guest

    On 15/08/2012 19:03, Alfred Molon wrote:
    My spectacle lens is OK, but it doesn't have the complexity (or the
    relative lack of chromatic aberration) of any camera lens.
    David Taylor, Aug 15, 2012
  4. That's an interesting comment but it does not seem to matter and no
    spectacle lens, even glass, is corrected for chromatic aberration, AFAIK.
    James Silverton, Aug 15, 2012
  5. Bob  AZ

    David Taylor Guest

    I tend to notice CA as one of my lenses has a particularly strong
    correction. BTW: I was delighted to change from glass to plastic, as
    the thickness and hence weight was very much reduced. In spite of being
    "plastic", the lenses appear reasonable scratch-proof in normal use.

    I guess the lens would need to be made as a compound lens to have any
    chance of CA being corrected, so I accept your comment.
    David Taylor, Aug 15, 2012
  6. Bob  AZ

    Me Guest

    I'm not a lens designer, and don't ask me for cites on these comments -
    if I'm wrong then I defer, but some general comments "AFAIK":

    Prejudice against "plastic" lens elements because of mechanical
    properties is probably unfounded. Some optical glass, particularly low
    dispersion ED and fluorite have horrible mechanical properties.

    Plastics can have good clarity and high refractive index, but tend to be
    high dispersion.

    It's very difficult to grind aspherical elements out of a blank piece of
    optical glass = expensive. A lens that you can't afford to buy isn't
    much use to you.

    The plastic "compound" elements tend to be used in wide - normal and
    ultra-wide zooms. These lenses were unobtainable in the past, even fast
    wide primes were very very expensive.

    Nikon (and others?) now can use precision glass moulding to cast
    aspherical elements, at lower cost than grinding the elements out of a
    glass blank (or to make lens elements that weren't practically possible
    to grind to shape), but this technology hasn't filtered down to
    mainstream lenses (Nikon use pgm in the 14-24, but I think the newer
    16-35mm f4 reverts to "hybrid" lens elements like the 17-35, Canon's
    17-40, 16-35mm etc. You can see from optical tests that the 14-24 is
    "better", particularly mtf at large apertures toward the edges of the frame.

    IMO zoom is much more useful - for composition - at wide angle / ultra
    wide angle focal lengths than at longer focal lengths. If "plastic"
    elements weren't used, then some of the great affordable wide-normal
    "kit" lenses and ultra-wide angle zooms, including "pro grade", would
    never have been made.

    Are these "high quality"? Probably not good enough for measurebaters
    and brick-wall photographers with very large budgets, but for most
    photographers I think they are.
    Me, Aug 15, 2012
  7. Bob  AZ

    David Taylor Guest

    More likely, in this case, the thickness is required to accommodate the
    curvature required by the refractive index of the glass used.
    David Taylor, Aug 16, 2012
  8. That seems to be the case in the UK. I have a rather strong short sight
    prescription, and prefer glass lenses. They last longer and naturally
    block UV. My lenses in ordinary spectacle glass would be very thick at
    the edges. But there are high refractive index glasses available which
    allow them to be pleasingly thin.
    Chris Malcolm, Aug 17, 2012
  9. Bob  AZ

    Me Guest

    I think you'll find that the polymers used in "plastic" lenses actually
    block more UV (particularly UVA) than glass.
    The higher the refractive index, then generally the higher dispersion /
    lower Abbe value, so more CA, that goes for both glass and plastic.
    Depending on lens prescription and frame, there might be no advantage to
    paying the price for extra high index lenses, the higher index material
    still needs to have a minimum thickness, and density increases with
    index, so you could end up with very expensive highest index lenses only
    marginally thinner, heavier, and with more CA than the cheaper ones. A
    good optician should be able to work this out and give you the right
    Me, Aug 17, 2012
  10. Well, I thought that's what my good optician had done. But I'll ask
    more questions next time. One thing which worries me is the appearance
    of the scratches on my lenses. Looking at them under a magnfying glass
    I can see a slight furrowing on some, with some raised edges. That
    looks like plastic deformation which shouldn't happen with glass. But
    perhaps they apply a special plasticcoating to the lens along with the
    anti-reflective etc. coating?
    Chris Malcolm, Aug 18, 2012
  11. Bob  AZ

    Me Guest

    The furrowing sound like a fault. There shouldn't be any deformation.
    I'm not certain, but the antireflective/scratch resistant coating would
    probably be one process.
    One local optician quoted my wife about $US1,000 for 1.76 RI lenses
    which he recommended (& frames made for a very expensive pair of
    glasses). A second opinion from another optician, after calculating
    everything he suggested that because of her prescription, there would be
    no (thickness/weight) advantage over 1.67 lenses - which were less than
    1/2 the price.
    After being presented with such a "bargain", of course she bought two pairs.
    The lenses are correcting astigmatism, long sightedness and are
    progressive bifocal. Even on discount web sites, by the time the
    prescription and options are selected, they are still not cheap, and
    it's important that the finished glasses are checked and frames adjusted
    Me, Aug 19, 2012
  12. Is it possible to make an affordable high-quality glass lens?
    David Dyer-Bennet, Sep 7, 2012
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