Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,338   Posts: 1,537,604   Online: 1065
      
Page 2 of 2 FirstFirst 12
Results 11 to 13 of 13
  1. #11

    Join Date
    Sep 2002
    Location
    Central Texas
    Shooter
    ULarge Format
    Posts
    67
    Yes Robert, that is what i am talking about. It does seem that the artars had different spacing if they came from the factory installed into a shutter. but I have not personally seen it.,??.
    huh?

  2. #12

    Join Date
    Dec 2002
    Shooter
    Large Format
    Posts
    6,242
    It would seem that the only way to determine the effect of different group spacing would be to use an optical bench. I do know that Steve Grimes (RIP) determined by micrometer measurement the spacing of the groups as they were in the barrel and he insured that this same spacing was maintained when he mounted the front and rear elements in the shutter. I assume, therefore, that there must be a good reason. Among those might be coma, spherical aberations etc. Those would not necessarily be readily apparent by viewing the "sharpness" on a ground glass.I have found, in my experience, that lens performance is readily apparent even on a contact print. Obviously the effects would be more noticeable as the degree of enlargement increases.
    Art is a step from what is obvious and well-known toward what is arcane and concealed.

    Visit my website at http://www.donaldmillerphotography.com

  3. #13

    Join Date
    Sep 2002
    Posts
    552
    The Kowa process lenses (which in some versions, as Computars also came mounted in shutters) come with little brass spacers and the following info:

    "Some times the barrel lens will come with thin spacers. The trick

    is this, for center image use, the more spacers between the rear cell and

    the shutter the better. For the corners of the image, no spacer is best.

    This is why, in a shutter mount, we often see one spacer as the best overall

    compromise."

    tim

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin