Re: Canon - Nikon Observations

On Fri, 09 Jan 2009 14:44:38 -0800, SMS <scharf.steven@xxxxxxxxxxx>
wrote in <uqQ9l.17964$ZP4.2724@xxxxxxxxxxxxxxxxxxxx>:

Larry Thong wrote:

Why would Nikon want to go backwards in optical technology? How many Canon
lenses went into space?

So that's your criteria for choosing lenses, which ones will work in space?

Yep! This is why NASA exclusively uses Nikkors. Canon lenses have a nasty
habit of the fluorite delaminating when tested under cold and low pressure
as in high altitude or the vacuum of space.

I'll keep that in mind the next time I plan a vacation or business trip
into space.

<http://imaging.nikon.com/products/imaging/lineup/lens/glossary.htm>

Nikon developed ED (Extra-low Dispersion) glass to enable the
production of lenses that offer superior sharpness and color
correction by minimizing chromatic aberration. Put simply, chromatic
aberration is a type of image and color dispersion that occurs when
light rays of varying wavelengths pass through optical glass. In the
past, correcting this problem for telephoto lenses required special
optical elements that offer anomalous dispersion characteristics --
specifically calcium fluoride crystals. However, fluorite easily
cracks and is sensitive to temperature changes that can adversely
affect focusing by altering the lens? refractive index. So Nikon
designers and engineers put their heads together and came up with ED
glass, which offers all the benefits, yet none of the drawbacks of
calcium fluorite-based glass.

Nikon ED is a silica glass which is fluorite loaded.
Nikon Super ED has a higher refractive index than fluorite.

--
Best regards,
John
Panasonic DMC-FZ8, DMC-FZ20, and several others
.

Relevant Pages

  • Re: Nikon and Canon Interleaved
    ... flourite is not a magical elixir that makes perfect lenses. ... calcium fluorite elements. ... cannot combine with silica readily and remain highly transparent. ... are the same as fluorite lens elements. ...
    (rec.photo.digital)
  • Re: Cost of fluorite versus ED glass
    ... Fluorite is a very brittle ... but we made a large number of lenses with fluorite and lost ... oriented using mostly machinery. ... kind of machining, dimond rough turning, polishing, inspecting etc..... ...
    (sci.astro.amateur)
  • Re: Canon 20D or Nikon D70s?
    ... >>dust protection is required to qualify also. ... > For example the 400mm f/5.6L has no fluorite elements. ... > Here is what Canon has to say about "L" lenses. ...
    (rec.photo.digital.slr-systems)
  • Re: Canon 20D or Nikon D70s?
    ... >>dust protection is required to qualify also. ... > For example the 400mm f/5.6L has no fluorite elements. ... > Here is what Canon has to say about "L" lenses. ...
    (rec.photo.digital.slr-systems)
  • Re: Canon 20D or Nikon D70s?
    ... Exotic elements, defined as exotic types of glass such as fluorite, or low dispersion glass, are needed for the lens to be considered an "L", according to Canon's own literature. ... I have read that all L lenses are sealed against the elements, ...
    (rec.photo.digital.slr-systems)
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