Lens transmission characteristics

Discussion in 'General Technical Discussion' started by Chris101, Dec 1, 2005.

  1. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    I just got a brand new Cary 50 spectrophotometer. So I thought I would look at the spectral transmission of a couple of my lenses. The following graph shows the 24-120VR lens vs the Schneider Componon-S 135mm f/5.6 enlarging lens:
    [​IMG]
    The Schneider does indeed have a bit more UV transmission (50% at 377 nm) but it is very flat throughout the visible range. By contrast the VR lens has enhanced blue transmission, something that may contribute to the 'snappy' color quality I find with that lens. I hope to get some time soon, and check out all my lenses.
     
  2. now I'm really lost
     
  3. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    There was some discussion a while back about the use of various lenses for pictorial UV work, so I was interested in the UV transmission of some of the lenses I've used with my home made, carbon arc lamp.

    This graph shows how much light of various wavelength is transmitted by the lens. Anything to the left of 400 is UV, 400 is violet, 460 is blue, 500 is green, 560 yellow, 600 orange and 670 is red. Anything over 700 is near IR.

    This particular graph shows the enlarging lens (Schneider) is pretty flat through the visible, down to blue where it starts to taper off, and it goes down to 377 into the UV. Not horrible, but not great either. In contrast the 24-120vr lens lets more blue through than it does red, and only goes down to 383 in the UV. Less good for UV use.
     
  4. Gale

    Gale

    978
    Jan 26, 2005
    Viera Fl
    Well Chris thanks for letting me know the good color with the 24-120 :>)) I love that lens ...
     
  5. Baywing

    Baywing

    Feb 22, 2005
    CT USA
    Chris, Do you know or know of Ron Wisner? He makes large format cameras in MA. I went to one of his workshops years ago and he is an optics nut. I have a feeling the two of you would get along very well. If not, at least you would have some interesting discussions.
     
  6. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  7. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    Hear, hear! If anyone wants to send me an exotic lens for spectral analysis, send it to me. Although the Cary will scan 190nm to 1100 nm in under 3 minutes (at the slowest speed) I'll need about four to six weeks for sample prep... :wink:
     
  8. cwilt

    cwilt

    Apr 24, 2005
    Denver, CO
    Thanks for taking the time to test and post this kind of information Chris. I hope you continue to test different lenses and let us know what you discover. It is this kind of informative posts that make the Cafe stand apart from the crowd. My 50/1.4 is glued to my D2x or I would send it to you for testing.:smile:

    Just recently I purchased Imatest and began testing my imaging system. Pixel peeping of this sort can be fun and constructive.

    Please keep up the good work.:smile:
     
  9. moffo

    moffo

    576
    Oct 20, 2005
    Central TX
    Hey, I used to drive a Cary! (Back when I was a chemist.) Tell me this is more than a hobby acquisition...
     
  10. But it would appear that the Schneider would capture a much more natural color spectrum.
     
  11. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    :biggrin: Ha! :biggrin: I wish! :biggrin:

    At $10K, this sucker's got to pay for itself!
     
  12. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    I don't know him. Very often people versed in the optical arts find me whack, because my understanding is simplistic and often guided by only the very basic sources. But I'm very open to learning.

    And I always try to have interesting conversations. Should the opportunity come up, I will seek out Ron Wisner.
     
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