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Thread: Coating colour question?

  1. #1

    Join Date
    Nov 1999
    Posts
    763

    Coating colour question?

    I recently purchased two absolutely beautiful commercial Ektar lenses dated sometime in 1947 [ES] and both of these lenses have a very distinct "blue" coating appearance. I also have a 12" Commercial Ektar in a barrel - again sometime in 1947- but a later production due to the higher number after the ES. This Ektar has a very different coloured coating, it is a brown/yellow/purpleish colour when viewed straight into the lens.

    All lenses are luminised with the L in the circle. Images are identical no matter which lenses is used so I was wondering if anyone has any thoughts. I'm referring to black and white images. Contrast and sharpness are the same for all lenses.

    One of the lenses is marked ES 180 whereas the other the serial # is ES 630

    Just a curiosity someone may have a thought on.

  2. #2
    Craig T
    Join Date
    Jul 2008
    Location
    Australia
    Posts
    347

    Re: Coating colour question?

    I think they are ALL broken Steve...better send em up here to me

  3. #3

    Join Date
    Jan 2010
    Location
    Elk Grove, California
    Posts
    51

    Re: Coating colour question?

    Steve, my recollection is that the early lense coatings were blue. I've only one commercial Ektar, an 8.5" with an RA number; it's coating is purple as is the 127mm Ektar that I bought in 1953. I'd surmise that your lenses spanned the change from the early coating to later formulas.

  4. #4

    Join Date
    Nov 1999
    Posts
    763

    Re: Coating colour question?

    Hi Craig the lenses would survive the trauma of going to Queensland and I agree with you Robert that the lenses are probably very early on in the Kodak coating regime. I had heard that the earlier coatings were/are softer. If that is the case these have had a very privileged life in their 63 years as there is not a single mark on them anywhere.

  5. #5

    Join Date
    Dec 2009
    Location
    Montréal
    Posts
    100

    Re: Coating colour question?

    I've driven myself crazy with this kind of thing before. I purchased a 90mm Leitmeyr a while back that had a distinctly blue/cyan cast in 3/4 reflections, but wasn't marked with an 'o' to indicate coating. I had only ever seen purple/amber reflections in single coated lenses before, and my Kodak Anastigmat from the '20's had a much more subtle but still obviously cyan reflection in one element, so it was maddeningly confusing.

    I actually eventually bought another 90mm Leitmeyr with the 'o' marking just to compare, and while the latter one's reflections are a little more purple, they're fairly similar. No obvious conclusions, but I'm leaning towards believing the first has an earlier version of coating. At some point, I'll do some image tests to confirm.

  6. #6

    Join Date
    Nov 2007
    Location
    Nuremberg Germany
    Posts
    1,048

    Re: Coating colour question?

    The hue of the coating depends not only on the thickness of the layer itself but also on the refractive index of the glass below the coating. And of course the refractive index of the layer e. g. Lithiumfluoride together with the incident angle of the light.

    In any case a more bluish or more amber hue has only a little influence if slide-film is exposed with such a lens but not on the contrast or transmission resp. exposure-time.

    Peter

  7. #7

    Join Date
    Mar 2006
    Location
    Austin, TX
    Posts
    435

    Re: Coating colour question?

    Kodak's original lens coating had a yellowish or golden cast, the B&J lenses had a bluish or purplish cast, the multicoated coatingings have lots of different casts, who cares they don't change the color of the image unless this is desired by the manufacturer to correct for another problem.

    Some of the "dyed in mass" glass filters were so poorly corrected that they used colored coatings to deliberately correct the color of the glass.

    Lynn

  8. #8

    Join Date
    Jun 2011
    Location
    Torrevieja, Spain
    Posts
    173

    Re: Coating colour question?

    by chance, I've discovered the front lens of my just acquired Caltar II-E is red ruby, as you can see in attached image.

    Just out of curiosity, what the red colour in the coating means?


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