Results 1 to 5 of 5

Thread: Lens coating & terminology evolution

  1. #1

    Join Date
    Feb 2015
    Location
    Colorado
    Posts
    307

    Lens coating & terminology evolution

    I've read with interest this old thread about lens coating which included much about the history and evolution of lens coatings. It also uncovers how the terms used for "coatings" have evolved.

    http://www.largeformatphotography.in...hlight=coating

    The coatings of Japanese lenses (as opposed to Japanese cameras with German lenses) appears to have occurred after WWII. Supposedly, Minolta was the first Japanese lens manufacturer to produce coated lenses -- a single coat in 1946 (the Semi IIIa era). I assume it was a layer of magnesium fluoride, but that doesn't mean that all of the elements and all sides of all elements were coated. Fuji lenses, at least their large format ones, started to get a coating around 1954. Again, I assume it was a single layer of magnesium fluoride. In 1958, Minolta pioneered its "Achromatic coating" which was two layers of magnesium fluoride deposited in different thicknesses. I have no details if this means two layers of different thicknesses on the same glass surface or two different layers on two different surfaces. They were using the term "Achromatic coating" well into the 1970's on lenses that were obviously multi-coated with different minerals. Each of Fuji's and Minolta's lens coatings (and undoubtedly everyone else) changed with their new series of lenses (ex. Minolta's Rokkor, Auto-Rokkor, Rokkor-X, Yashica's ML, MC, DX, and Fuji's SW, SWD, W, NW, CM-W), but there is plenty of evidence that the coatings changed/improved even within the same series.

    But is begs the question, "What consitutes multi-coating?" Minolta had lenses with two coats of magnesium fluoride. They didn't call it multi-coating, but it seems that it qualifies. On their enlarging lens spec sheets, they lists some some coatings as "amber", and others as "amber and magenta", but none as "multi coated". "amber and magenta" are obviously at least two coatings, but the "amber" lenses might have been more than one layer, too.

    At some point, Minolta started to use the word "multi-coated". Fuji called their approach EBC (electorn beam coating). Tamron BBAR (Broad-Band Anti-Reflection) coating -- up to seven layers on glass-to-air surfaces. Most people would think that all lens elements get the same treatment/coating. To me, all this means is that SOME elements of all of these multi-(more than one)-coated lenses may have a lot of coatings, but others may have only one layer (or perhaps none?).

    I've had the Fujinon f5.6 105mm EBC in the NW and CM-W. The NW version appeared multi-coated on the front and single-coated on the rear, while the CM-W version appears multi-coated on both. I'm not surprised since they are different optical designs. The same with my Fujinon f5.6 75mm EBC SWD -- it appears multi-coated on the front and single-coated on the rear. Some Carl Zeiss T* lenses have little multi-coating.

    So it appears that "multi-coated" is apparently a very loose term. Sometimes lenses that have quite a lot of multi-coating are not labeled as multi-coated, but some that are labeled multi-coated have limited multi-coating.

    Multi-coating -- More than one coating on any surface? More than one coating on more than one surface? More that one type of mineral?

  2. #2

    Join Date
    May 2007
    Location
    Greenwood Lake NY USA
    Posts
    109

    Re: Lens coating & terminology evolution

    Some technical information here from Edmund Optics https://www.edmundoptics.com/resourc...-notes/optics/

  3. #3
    Greg Davis's Avatar
    Join Date
    Nov 2009
    Location
    Kentucky
    Posts
    401

    Re: Lens coating & terminology evolution

    There two different methods of applying a coating on a lens to reduce reflections. The method I use at work involves adding a clear coating that is uv cured, then placing it in a vacuum chamber. While it is in under vacuum it is bombarded with a spray of argon gas that creates micro abrasions in the clear coating I applied earlier. This is done in six different layers, some machines apply up to 14 layers. The color of the resulting lens is controlled by the mix of argon and nitrogen used. Every manufacturer likes a different color. Minolta/Sony likes green, Rodenstock likes red, Schneider likes purple/blue. The Kodak lenses I have seen are yellow.

    The other method I have seen adds the coating under vacuum directly rather than by argon abrasion like my machine. Camera lens elements most likely use the second method as the elements are glass as opposed to plastics.

  4. #4

    Join Date
    Sep 1998
    Posts
    10,163

    Re: Lens coating & terminology evolution

    Quote Originally Posted by Greg Davis View Post
    There two different methods of applying a coating on a lens to reduce reflections. The method I use at work involves adding a clear coating that is uv cured, then placing it in a vacuum chamber. While it is in under vacuum it is bombarded with a spray of argon gas that creates micro abrasions in the clear coating I applied earlier. This is done in six different layers, some machines apply up to 14 layers. The color of the resulting lens is controlled by the mix of argon and nitrogen used. Every manufacturer likes a different color. Minolta/Sony likes green, Rodenstock likes red, Schneider likes purple/blue. The Kodak lenses I have seen are yellow.

    The other method I have seen adds the coating under vacuum directly rather than by argon abrasion like my machine. Camera lens elements most likely use the second method as the elements are glass as opposed to plastics.
    There are also steamed on coatings and not all camera lens elements are made of glass.

  5. #5
    Greg Davis's Avatar
    Join Date
    Nov 2009
    Location
    Kentucky
    Posts
    401

    Re: Lens coating & terminology evolution

    That would be beyond my knowledge. I don't work with camera lens manufacturing.

Similar Threads

  1. Nikkor SW 120/8 - any evolution within last 20 yrs?
    By Torsten in forum Lenses & Lens Accessories
    Replies: 1
    Last Post: 22-Sep-2008, 13:58
  2. Terminology at the front of a view camera.
    By Doug Kerr in forum Cameras & Camera Accessories
    Replies: 8
    Last Post: 10-Nov-2006, 22:20
  3. Lens terminology
    By Jim Grimes in forum Lenses & Lens Accessories
    Replies: 16
    Last Post: 12-Jul-2006, 17:08

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •