UV filter applied on CCD/CMOS (Nikon D80) ?

Discussion in 'Nikon' started by Lorenzo Sandini, Oct 22, 2008.

  1. I am almost embarrassed looking at the dimensions this thread is taking.

    I was quite happy with Floyd's answer, except for the Google suggestion.
    I guess most people google before they post in here, don't they ?

    And since I don't know the background of your ongoing argument, I think
    we can close it, since it doesn't bring anything more to the topic.
    Thank you both for contributing anyway :)

    Thanks to everyone else too, I got more answers than my brain-stomach
    can digest for now.

    Lorenzo
     
    Lorenzo Sandini, Oct 23, 2008
    #21
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  2. Lorenzo Sandini

    Eric Stevens Guest


    Aah - if that is all that you do.

    But you post incomplete quotes, distort what has been said.
    misrepresent who said what, make false allegations and - above all
    this - you strive to maintain an atmosphere of arrogant superiority.
    We've met before on sci.archaeolgy, before you were driven out, but
    this time you are down-the-toilet material from the outcome.



    Eric Stevens
     
    Eric Stevens, Oct 23, 2008
    #22
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  3. Doug Jewell wrote:
    []
    Are there any natural objects which do this - some flowers, for example?

    David
     
    David J Taylor, Oct 23, 2008
    #23
  4. Should have stayed with Nikon! <G>

    Interesting experiment you propose on darkening the sky. Watch out for
    low signal-to-noise ratio in the blue channel, though.

    David
     
    David J Taylor, Oct 23, 2008
    #24
  5. Scorpions ?

    Lorenzo
     
    Lorenzo Sandini, Oct 23, 2008
    #25
  6. Except of course in those non-reflex viewfinders which don't use the
    camera objective lens, the objective image forming lens in the
    viewfinder. And except, in the case of stand alone rangefinders with
    their own optics, the objective lens of the rangefinder, and so on. A
    rangefinder Leica, for example, will therefore have three objective
    lenses, the camera objective, the viewfinder objective, and the
    rangefinder objective.
     
    Chris Malcolm, Oct 23, 2008
    #26
  7. A fluorescent material absorbs optical energy at a higher wavelength,
    and emits it at a lower wavelength. If (as is usually the case) it is
    also coloured at the lower emitting wavelength, this enables it to
    show a colour which is brighter than could possibly be accounted for
    by simple reflecting of a colour under the prevailing light. So a
    fluorescent red is red because it reflects red, and even redder
    because it also reflects ultraviolet as red too.

    Some flowers do this. It's particularly common in the geranium family.
     
    Chris Malcolm, Oct 23, 2008
    #27
  8. Chris Malcolm wrote:
    []
    Thanks, Chris.

    For a moment, I was confusing fluorescence with the effect I have seen
    when photographing some blue flowers and some fabrics with digital cameras
    where the colour rendering is noticeably incorrect. I saw this on quite
    early digital cameras, and it hasn't bothered me since (but I'm not that
    sensitive to the absolute hue of flowers - not being a keen gardener). At
    the time, I seem to recall that the issue was that the camera RGB did not
    have quite the same spectral response curves as the eye (if that's a
    meaningful statement) - and of course the more fundamental differences
    between those sensors!

    Cheers,
    David
     
    David J Taylor, Oct 23, 2008
    #28
  9. I agree with your comments, but you can also observe the
    effect by observing unbleached white flour. Paper just makes
    it a bit easier (and doesn't require cleaning the filter).

    Or you can cheat and go directly to the source. Here are
    Hoya's own specs for it's L37 UV filter material. Note that
    the graph is for uncoated material:

    http://www.hoyaoptics.com/pdf/L37.pdf

    At 400nm, internal transmission is 93.8%, and at 420nm, it's
    98.5%. More aggressive materials like Nikon's old L39 filter
    can even block a small percentage of green light.

    B+W also provides a similar transmission curve for its 010
    UV filter:
    http://www.schneideroptics.com/pdfs/filters/FilterTransmissionCurves.pdf
    http://snipurl.com/4mnfe [www_schneideroptics_com]

    Multicoating changes spectral response slightly, and even worse
    the response changes with light angle. Most filter manufacturers
    treat their multicoating process as a deep trade secret, but
    here's a graph from one specialty firm for a 4-layer coating:

    https://www.omegafilters.com/index.php?page=tech_app_notes

    In practice this level of difference is rarely significant. But
    it explains in part how some lenses can be "cooler" or "warmer"
    than others. Even so, you're almost always better off with a
    multicoated filter than a single coated one.

    In these discussions, people tend to exaggerate the benefits of
    a clear filter over a UV filter. If anyone is interested, I can
    provide a link to a pair of shots in .NEF format shot under
    controlled lighting, one with a Nikon L37c and one without. It
    takes a lot of work to detect the difference.

    But as small as the downside may be for a UV filter, with this
    modern gear there is no compensating upside. The salesman made
    the correct recommendation.
     
    Michael Benveniste, Oct 23, 2008
    #29
  10. Other languages, other customs. In many languages "lens" refers to the
    single lens element while the assembly that we mount on front of the
    camera is known as an "objective". As Lorenzo appears to be Finish, you
    may want to cut him some slack.

    Aside, wouldn't it be nice to be able to differentiate between lense and
    lense without having to fall back to substitute terms like element or
    assembly, don't you think?

    jue
     
    Jürgen Exner, Oct 23, 2008
    #30
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