Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: Lens coating test

  1. #1

    Join Date
    Oct 2003
    Location
    St. Simons Island, Georgia
    Posts
    792

    Lens coating test

    I have a lens that has “spots” in the front coating. Cleaning does not remove them. I want to test to see if they cause problems in the image, so what should I photograph for the tests? Clear open sky, an evenly lighted smooth wall? I shoot mostly landscapes so the lens will be used at longer distances.

  2. #2

    Join Date
    Feb 2001
    Location
    Greenbank, WA
    Posts
    2,457

    Re: Lens coating test

    Generally this is not a problem. Try a relatively dim room interior, expose for the interior, but have an open door or a window with much brighter light on the outside. Unless you have the same lens with no coating spots, it may be hard to interpret the results since you have no control. When evaluating "cleaning marks" I can usually look at a bright distant light through the lens. If the light looks hazy or fuzzy they are significant. There will be some reduction in contrast using the lens.

    Or, keep it simple. Go photograph a landscape under typical conditions and see if you like the result. Throw in some bright highlights.

  3. #3

    Join Date
    Feb 2009
    Posts
    250

    Re: Lens coating test

    Quote Originally Posted by j.e.simmons View Post
    I have a lens that has “spots” in the front coating. Cleaning does not remove them. I want to test to see if they cause problems in the image, so what should I photograph for the tests?
    You shouldn't photograph anything for that type of test. The influence of those spots is so negligible that it is not detectable by any modern precision measuring instruments - to say nothing of an actual picture taken by the lens.

    Even if you compare two identical lenses with and without the spots, the difference between them would depend on the degree of their glass cleanness, not on the spots you describe. (And you'll have to spend about an hour cleaning EACH glass surface with ether before you start testing the pair of lenses by the way.... but no you will not see any difference still.)

  4. #4

    Join Date
    Nov 2017
    Posts
    295

    Re: Lens coating test

    nighttime street photography. if street lights, cars and shop windows don't cause any problems, nothing will. take at least one shot with some out of focus small lights to see if the spots are visible or not.

  5. #5
    Alan Klein's Avatar
    Join Date
    Jun 2015
    Location
    New Jersey was NYC
    Posts
    1,750

    Re: Lens coating test

    Have you tried ROR? It cleans stuff that normal lens cleaner won;t clean.
    https://www.bhphotovideo.com/c/produ...saAr1QEALw_wcB

  6. #6
    Alan Klein's Avatar
    Join Date
    Jun 2015
    Location
    New Jersey was NYC
    Posts
    1,750

    Re: Lens coating test

    I have a mark on the back of my LF lens, a 75mm. How would I check out how it affects the photos?

  7. #7

    Join Date
    Sep 1998
    Location
    Loganville , GA
    Posts
    14,272

    Re: Lens coating test

    Quote Originally Posted by Alan Klein View Post
    I have a mark on the back of my LF lens, a 75mm. How would I check out how it affects the photos?
    Use it and see.

  8. #8

    Join Date
    Oct 2003
    Location
    St. Simons Island, Georgia
    Posts
    792

    Re: Lens coating test

    The MSDS of the recommended ROR says it includes alcohol and ammonia. I’ve read warnings against using both of those chemicals. Can this really be safely used?

  9. #9
    Alan Klein's Avatar
    Join Date
    Jun 2015
    Location
    New Jersey was NYC
    Posts
    1,750

    Re: Lens coating test

    Quote Originally Posted by Bob Salomon View Post
    Use it and see.
    Well I haven't noticed any bad results. But maybe I have to try it on a blank wall or maybe a black wall or whatever to bring out the defects. Is there a procedure to do that?

  10. #10
    Mark Sawyer's Avatar
    Join Date
    Jul 2004
    Location
    Stuck inside of Tucson with the Neverland Blues again...
    Posts
    6,088

    Re: Lens coating test

    Quote Originally Posted by j.e.simmons View Post
    I have a lens that has “spots” in the front coating. Cleaning does not remove them. I want to test to see if they cause problems in the image, so what should I photograph for the tests?
    Anti-reflective coatings are primarily to reduce flare, so photograph in a situation where flare is a major issue, such as into the sun. Problem is, as ridax said, without a similar image from a perfect lens, you have nothing to compare the results to.

    On the bright side, since the spot is on the front element, any reflected light will reflect outward and have no effect. Inside the lens, light starts bouncing around, and that's where you might see some effect. But honestly, I wouldn't expect much difference even there.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

Similar Threads

  1. lens coating defects
    By natek83 in forum Lenses & Lens Accessories
    Replies: 14
    Last Post: 13-Jan-2010, 01:00
  2. Lens coating damage
    By Steve Clark in forum Lenses & Lens Accessories
    Replies: 7
    Last Post: 29-Jan-2005, 20:00
  3. Lens coating damage
    By Huw Evans in forum Lenses & Lens Accessories
    Replies: 7
    Last Post: 11-May-2001, 13:51
  4. G Claron Lens Coating
    By Douglasa A. Benson in forum Lenses & Lens Accessories
    Replies: 5
    Last Post: 6-Oct-2000, 19:47
  5. Lens coating on G-Clarons
    By Dick Clark in forum Lenses & Lens Accessories
    Replies: 4
    Last Post: 4-Jan-2000, 04:19

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
  •