Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,818   Posts: 1,581,645   Online: 802
      
Page 3 of 5 FirstFirst 12345 LastLast
Results 21 to 30 of 46
  1. #21
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,521
    Images
    65
    Quote Originally Posted by Q.G. View Post
    Both however are the result of one and the same thing.
    If you have a measure of that (spread), you'll know about both bloom and fill.



    The OP asked about a way to test a lens.
    I answered the OP with a complete description of testing.

    As for fill and spread they are aspects of the same thing but are manifested differently as a function of line width and "polarity" of the original. You would see that if you ran the tests.

    PE

  2. #22
    RalphLambrecht's Avatar
    Join Date
    Sep 2003
    Location
    Central florida,USA
    Shooter
    Multi Format
    Posts
    6,791
    Images
    1
    Quote Originally Posted by Grif View Post
    Hey,,, good job. I finally went thru most of them,
    http://www.edmundoptics.com/onlineca...productID=1665

    Is also an affordable item I'll likely add to the order with the small resoulution target.
    Yes, this one includes the resolution table, which you need to quantify your results by multiplying it with the inverse of your imaging scale. You'll also find the table here:

    http://www.darkroomagic.com/Darkroom...utionChart.pdf
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  3. #23

    Join Date
    Aug 2009
    Location
    Selah, WA
    Shooter
    Multi Format
    Posts
    255

    Fill/Spread Question-Comments

    Quote Originally Posted by Photo Engineer View Post
    I answered the OP with a complete description of testing.

    As for fill and spread they are aspects of the same thing but are manifested differently as a function of line width and "polarity" of the original. You would see that if you ran the tests.

    PE
    If I understand correctly,,, fill/spread are the terms for diffusion on the lens, and diffusion at the enlarger? Light spreads into the shadows,,, or shadow fills into the hilights?

    I think that's when I first got the difference, but I sure don't remember them being referred to as fill and spread back before grey hair. I just remember going, wow, that didn't turn out like I thought in the dark room one day.

  4. #24
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,521
    Images
    65
    Fill and spread are primarily film/process effects. The lenses involved govern flare for the most part.

    PE

  5. #25

    Join Date
    Jul 2007
    Location
    Netherlands
    Shooter
    Medium Format
    Posts
    5,686
    Dark can't and doesn't spread, so the effects fill and bloom are both caused by light spreading.
    Bloom is light creating a fuzzy edge between bright and dark areas where there should be a sharp one. Fill is where the bloom of adjacent bright areas touch, filling in the dark bit inbetween.

    The spread is a function of how a lens transmits light. (Flare is something different.)
    Or of how light is diffused inside an emulsion.
    To test a lens alone, you have to look at the aerial image it produces of a test target.
    If you want to test the effect of the film too, you have to examine the recorded image on film (which has to be developed before you can see it, so you will be seeing the effect of development too).
    If you want to test the effect of the paper, [etc.]

  6. #26
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,521
    Images
    65
    QG;

    Bloom and fill are chemical effects in film and are related to the type of image, the chemistry involved and the emulsion being used. Both a negative and positive resolution chart are used to check out these effects. Fundamentally, one is related to macro contrast and the other is related to micro contrast.

    Turbidity of the emulsion governs internal reflections and therefore affects the sharpness of the exposure.

    Bloom makes a 1 micron line appear wider but often have less density than it should. It is a dark line on a white background on the negative. Fill makes a 1 micron line appear narrower and have less density than it should. It is a light line on a dark background. If you reason this through, you will understand the effects gong on.

    PE

  7. #27

    Join Date
    Jul 2007
    Location
    Netherlands
    Shooter
    Medium Format
    Posts
    5,686
    Bloom and fill are not just chemical effects, PE.

  8. #28
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,521
    Images
    65
    Bloom and fill are not just optical effects. They must be tested properly for all varieties of effects. Generally, you will find that the chemical effects tend to overwhelm any optical consideration when using high quality professional equipment.

    PE

  9. #29

    Join Date
    Jul 2007
    Location
    Netherlands
    Shooter
    Medium Format
    Posts
    5,686
    PE,

    You're right about the 'chemicals' being more of a limiting factor than the optics are in an reasonably ideal scenario. (More often it's the optics though.)

    Anyway, the OP asked about testing a lens.
    An often used measure for lens' performance is the MTF graph. Which is about nothing but bloom and fill - the optical effect. Spread.

  10. #30

    Join Date
    Aug 2009
    Location
    Selah, WA
    Shooter
    Multi Format
    Posts
    255
    Ok, getting closer. My example of "printing" or "exposing" were more examples of two different types of flare, whither induced on purpose or by accident, right?

    Bloom and fill are effects that occure within the emulsion, both chemical and optical?

Page 3 of 5 FirstFirst 12345 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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