Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 74,468   Posts: 1,644,098   Online: 713
      
Page 3 of 3 FirstFirst 123
Results 21 to 28 of 28
  1. #21
    Jaime Marin's Avatar
    Join Date
    Jul 2011
    Location
    California
    Shooter
    35mm
    Posts
    61
    Quote Originally Posted by Michael W View Post
    I would give 3 stops more than the meter reading.
    Does the filter have the filter factor engraved on the ring? If it says "x8" then that confirms 3 stops.

    I actually dont know I have yet to purchase it

  2. #22
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,960
    Images
    51
    I couldn't find the two-stop recommendation on the Tiffen site within a few minutes looking.

    x8 (three stops) used to be printed on the slip of paper you got with your typical filter.
    -If you want to keep it simple you can use that factor and be fine.

    Adrian mentioned the instructions and chart from Gordon Hutchings.
    -In the specific example of the 25 Red filter, AFTER reading through the filter, you open up an ADDITIONAL two stops.

    Hutchings method sounds like a good way to go.

  3. #23
    Leigh B's Avatar
    Join Date
    Jan 2011
    Location
    Maryland, USA
    Shooter
    Multi Format
    Posts
    1,035
    Images
    1
    Here's a table of filter factors and the corresponding f/stop correction:

    Fact..Stops
    1.0...0.0
    1.5...0.6
    2.0...1.0
    2.5...1.3
    3.0...1.6
    3.5...1.8
    4.0...2.0
    4.5...2.2
    5.0...2.3
    5.5...2.5
    6.0...2.6
    6.5...2.7
    7.0...2.8
    7.5...2.9
    8.0...3.0
    8.5...3.1
    9.0...3.2

    This derives from the relationship between factor and stops thus: factor = 2^(stops).

    So the factor for 1 stop = 2^1 = 2; the factor for 2 stops = 2^2 = 4; the factor for 3 stops = 2^3 = 8; the factor for 4 stops = 2^4 = 16.

    Going the other way, stops = log(factor)/log(2).

    A filter factor of 3 corresponds to a correction of about 1 2/3 stops (actually 1.585).

    B+W shows a filter factor of 5 for their light red (25) filter, which is about 2 1/3 stops (2.322).

    - Leigh
    Last edited by Leigh B; 12-25-2011 at 11:57 PM. Click to view previous post history.
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  4. #24
    Helinophoto's Avatar
    Join Date
    Aug 2011
    Location
    Norway
    Shooter
    Multi Format
    Posts
    597
    Images
    20
    According to this article on wikipedia, 25A has a factor of 5, which is slightly over 2 stops http://en.m.wikipedia.org/wiki/Filter_factor , i have hoya and opening up roughly 2 stops worked fine for me.
    -
    "Nice picture, you must have an amazing camera."
    Visit my photography blog at: http://helino-photo.blogspot.com

  5. #25
    Jaime Marin's Avatar
    Join Date
    Jul 2011
    Location
    California
    Shooter
    35mm
    Posts
    61
    Quote Originally Posted by Helinophoto View Post
    According to this article on wikipedia, 25A has a factor of 5, which is slightly over 2 stops http://en.m.wikipedia.org/wiki/Filter_factor , i have hoya and opening up roughly 2 stops worked fine for me.
    awesome this was great ! Thanks everyone for the input

  6. #26

    Join Date
    Apr 2008
    Location
    Los Angeles, CA
    Shooter
    Multi Format
    Posts
    8,006
    Images
    4
    Quote Originally Posted by Helinophoto View Post
    According to this article on wikipedia, 25A has a factor of 5, which is slightly over 2 stops http://en.m.wikipedia.org/wiki/Filter_factor , i have hoya and opening up roughly 2 stops worked fine for me.
    And according to this one (http://en.wikipedia.org/wiki/Wratten_number) 25A has a filter factor of 8. Thus my comments to check the recommendations of each filter manufacturer.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  7. #27
    Leigh B's Avatar
    Join Date
    Jan 2011
    Location
    Maryland, USA
    Shooter
    Multi Format
    Posts
    1,035
    Images
    1
    Another point to consider is that monochrome contrast filters will not have the same factor with all films.

    It varies with the spectral sensitivity of the individual film. That's particularly true at the red end of the spectrum.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  8. #28

    Join Date
    Nov 2011
    Location
    Plymouth, UK
    Shooter
    Multi Format
    Posts
    348
    As stated it's very dependant on film and film speed/developer, the latitude of the film will also take care of minor differences between makes of filter I tend to use +1 stop for yellow, +2 for orange and +3 for red. Seems to work okay.

Page 3 of 3 FirstFirst 123


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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