Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,901   Posts: 1,584,475   Online: 949
      
Page 1 of 5 12345 LastLast
Results 1 to 10 of 44
  1. #1

    Join Date
    Jun 2004
    Location
    South Norfolk, United Kingdom
    Shooter
    Multi Format
    Posts
    2,918
    Images
    66

    Comparative reciprocity failure of available sheet films

    While I have read that Kodak TMY-2 has good reciprocity characteristics and the Fomapan films show very significant reciprocity failure; the ILFORD data sheets for HP5+, FP4+, and Delta 100 all seem to show the same reciprocity characteristics through a rather imprecise and limited graph.

    A photo.net contributor has published a formula to calculate reciprocity failure of Delta 100 'Corrected time = 1.15567 x (Metered time)^1.4379'; however, I have seen little in way of comparison between HP5+, FP4+, and Delta 100. Does a lack of comparison indicate these films all have the same reciprocity characteristics, which seems unlikely...?

    Tom.

  2. #2
    Thomas Bertilsson's Avatar
    Join Date
    Jan 2003
    Location
    Minnesota
    Shooter
    Multi Format
    Posts
    14,560
    Images
    300
    Howard Bond published an article on this with some very useful information. I believe it was Photo Techniques in 2003. I don't have a copy on hand, unfortunately.
    It included Tri-X 400, Tmax 400, Tmax 100, 100 Delta, and HP5+. That was the old version of Tmax 400, of course.
    Tmax 100 and 100 Delta were the most linear of the bunch. But TMY is two stops faster... HP5 and Tri-X were the worst performers. Another conclusion was that no compensation in development needed to be done, which is good news.

    100 Delta and HP5 definitely did not have the same reciprocity characteristics, according to Bond's test.

    You'll have to locate the article somehow.

    - Thomas
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  3. #3

    Join Date
    Mar 2005
    Location
    Germany
    Shooter
    Medium Format
    Posts
    531
    Images
    133

  4. #4
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,435
    Images
    148
    Thanks Ulrich, that's the most useful article I've seen in a long while. I'll make a precis of the data to keep with my lenses.

    Ian

  5. #5

    Join Date
    Mar 2008
    Shooter
    4x5 Format
    Posts
    82
    Images
    2
    Tom,
    In case you are interested, Fuji's boast that Acros 100 shows very little reciprocity failure seems to have something to it--which I found out quite by accident. I don't recall whether the sheet included with the box of 4x5 provides extensive information for it, though, although that may be available elsewhere.
    Le-qun

  6. #6

    Join Date
    Mar 2005
    Location
    Germany
    Shooter
    Medium Format
    Posts
    531
    Images
    133
    I recently suggested in a German forum already to collect data on reciprocity-failure. It seems to me more valuable than information on developing times in respect to certain developers, as it's inherent to the respective film, largely independent from individual influences and moreover difficult to test without the proper equipment.

    Ulrich

  7. #7
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    Search www.unblinkingeye.com for "LIRF is Lurking at Your F-stop" by Patrick Gainer. It shows some interesting facts about reciprocity obtained by analyzing Howard Bond's data in an unusual manner.
    Gadget Gainer

  8. #8

    Join Date
    Sep 2008
    Shooter
    35mm
    Posts
    13
    Quote Originally Posted by An Le-qun View Post
    Tom,
    In case you are interested, Fuji's boast that Acros 100 shows very little reciprocity failure seems to have something to it--which I found out quite by accident. I don't recall whether the sheet included with the box of 4x5 provides extensive information for it, though, although that may be available elsewhere.
    Le-qun

    I've tested this film for astrophotography and it does have very good reciprocity characteristics. I could see that density of nebula was still building against background in test exposures up to 32 minutes. For terrestrial shooting this just goes to show that it does indeed have excellent performance, likely the best on the market with LIRF in mind. Fuji boasts no reciproity adjustment for exposures up to two minutes. I plan further tests but I'm a little concern about how easily it seems to scratch; I'm going to have to track that down.

  9. #9

    Join Date
    Mar 2005
    Location
    Germany
    Shooter
    Medium Format
    Posts
    531
    Images
    133
    Quote Originally Posted by gainer View Post
    Search www.unblinkingeye.com for "LIRF is Lurking at Your F-stop" by Patrick Gainer. It shows some interesting facts about reciprocity obtained by analyzing Howard Bond's data in an unusual manner.
    I just did a quick check with some data for HP5 from the Bond article. It really seems to work.

    Ulrich

  10. #10

    Join Date
    Jan 2009
    Shooter
    Large Format
    Posts
    50
    Quote Originally Posted by gainer View Post
    Search www.unblinkingeye.com for "LIRF is Lurking at Your F-stop" by Patrick Gainer. It shows some interesting facts about reciprocity obtained by analyzing Howard Bond's data in an unusual manner.

    Thanks for the article-

    using your graph for all films, the corrected exposure for an indicated time of 1 sec is 1.3 sec, for a time of 10 sec is 14 sec? am I doing this correctly? seems kind of low corrections for Tri-X in my experience- or I have been over-correcting...

Page 1 of 5 12345 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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