Nikon 1 lenses. Glass or Plastic?

On 15/08/2012 4:14 p.m., Bob AZ wrote:
Are the lenses for the new Nikon 1 cameras "glass or plastic"?

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?

On 15/08/2012 19:03, Alfred Molon wrote:
[]
Is it possible to make a high quality plastic lens?

My spectacle lens is OK, but it doesn't have the complexity (or the
relative lack of chromatic aberration) of any camera lens.
--
Cheers,
David
Web: http://www.satsignal.eu

On 8/15/2012 9:29 AM, David Taylor wrote:
On 15/08/2012 19:03, Alfred Molon wrote:
[]
Is it possible to make a high quality plastic lens?

My spectacle lens is OK, but it doesn't have the complexity (or the
relative lack of chromatic aberration) of any camera lens.

That's an interesting comment but it does not seem to matter and no
spectacle lens, even glass, is corrected for chromatic aberration, AFAIK.

--
Jim Silverton (Potomac, MD)

Extraneous "not" in Reply To.

In article , Me says...
Does it really matter?

Is it possible to make a high quality plastic lens?
--

Alfred Molon
------------------------------
Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

On 15/08/2012 19:01, James Silverton wrote:
On 8/15/2012 9:29 AM, David Taylor wrote:
On 15/08/2012 19:03, Alfred Molon wrote:
[]
Is it possible to make a high quality plastic lens?

My spectacle lens is OK, but it doesn't have the complexity (or the
relative lack of chromatic aberration) of any camera lens.

That's an interesting comment but it does not seem to matter and no
spectacle lens, even glass, is corrected for chromatic aberration, AFAIK.

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.
--
Cheers,
David
Web: http://www.satsignal.eu

On 16/08/2012 6:03 a.m., Alfred Molon wrote:
In article , Me says...
Does it really matter?

Is it possible to make a high quality plastic lens?

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.

David Taylor wrote in
:

On 15/08/2012 19:01, James Silverton wrote:
On 8/15/2012 9:29 AM, David Taylor wrote:
On 15/08/2012 19:03, Alfred Molon wrote:
[]
Is it possible to make a high quality plastic lens?

My spectacle lens is OK, but it doesn't have the complexity (or the
relative lack of chromatic aberration) of any camera lens.

That's an interesting comment but it does not seem to matter and no
spectacle lens, even glass, is corrected for chromatic aberration,
AFAIK.

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.


Because the nanny state mandates glass lenses be a specific thickness so
as not to be "dangerous."

On 16/08/2012 03:01, Rich wrote:
David Taylor wrote in
:
[]
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.


Because the nanny state mandates glass lenses be a specific thickness so
as not to be "dangerous."

More likely, in this case, the thickness is required to accommodate the
curvature required by the refractive index of the glass used.
--
Cheers,
David
Web: http://www.satsignal.eu

David Taylor wrote:
On 16/08/2012 03:01, Rich wrote:
David Taylor wrote in
:

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.

Because the nanny state mandates glass lenses be a specific thickness so
as not to be "dangerous."

More likely, in this case, the thickness is required to accommodate the
curvature required by the refractive index of the glass used.

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

On 17/08/2012 9:54 p.m., Chris Malcolm wrote:
David Taylor wrote:
On 16/08/2012 03:01, Rich wrote:
David Taylor wrote in
:

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.

Because the nanny state mandates glass lenses be a specific thickness so
as not to be "dangerous."

More likely, in this case, the thickness is required to accommodate the
curvature required by the refractive index of the glass used.

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.

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
advice.