Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,914   Posts: 1,584,705   Online: 745
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 23
  1. #1

    Join Date
    Jul 2014
    Shooter
    Medium Format
    Posts
    77

    Spots on negatives, chemical burn?

    I took a load of test shots around the house with my recently accuired SQ-Ai.

    Fomapan 200
    Tetenal Ultrafin 1+20 at 21'c for 7min, adgitate 30 seconds then 5 sec every min as per Massive Dev chart
    Ilfostop
    Ilford rapid fixer
    10 min wash with tap water and final dip in Photoflo

    Ten of the frames were fine but one has some odd spots on it that look a bit like chemical burns. I'm still new to this could anyone shed any light on what the marks are?


  2. #2

    Join Date
    Sep 2006
    Location
    UK
    Shooter
    35mm RF
    Posts
    3,550
    Use a loupe on the negative, is the surface of the gelatin damaged?

  3. #3

    Join Date
    Jul 2014
    Shooter
    Medium Format
    Posts
    77
    I don't have a loupe unfortunately. I've had a look with a magnifying glass (6x i think) and I cant see any blemishes on either side of the film. The marks seem to be in the image. As i turn the neg in the light they only appear as the rest of the image appears.

    Sent from my GT-I9505 using Tapatalk

  4. #4

    Join Date
    Feb 2012
    Location
    Penfield, NY
    Shooter
    35mm
    Posts
    1,090
    They might be air bubbles. After each agitation I always hit the tank against my palm several times to dislodge any air bubbles.

  5. #5

    Join Date
    Jul 2014
    Shooter
    Medium Format
    Posts
    77
    After each agitation I put the tank down and knock three times on the side to disslodge bubbles.
    One thing I forgot to mention is that this is the 11th exposure and there is a couple of hese marks on the 12th. These two frames would have been on the outside of the Patterson spool. I wonder if thats significant.

    Sent from my GT-I9505 using Tapatalk

  6. #6

    Join Date
    Sep 2006
    Location
    UK
    Shooter
    35mm RF
    Posts
    3,550
    If you are going to invert with a Patterson only use the minium liquid to submerge the reel.

    - for fix and dev
    - 10% less for stop, rinse, clear, 3x rinse and use continuous agitation

    agitation needs air space to allow a flow of developer over film.

    I never agitate dev, way too lazy.

    Unless you have bowed the film so that it was close, bubbles would not be grouped like that and you have doughnuts around the 'bubbles' which Id not expect.

    But I've never had any emulsion problems with Foma film either, hundreds of feet of bulk 35, hundreds of 135, 50x 120.

    120 is very difficult to load, be more gentle, try again.

  7. #7
    georgegrosu's Avatar
    Join Date
    Oct 2007
    Location
    Bucharest, Romania
    Shooter
    Multi Format
    Posts
    166
    What I see as faults in some circles closed (positive) which are
    surrounded by other larger circles - lighter.
    If it were only darker spots (positive) I would assume that comes from
    condensation on the negative.
    In this area accumulate the produced of film that have a lower pH
    and will change the pH of the developer in the area.
    Finally, negative density will be lower (in this area).
    That the positive will be closed.
    The problem with open areas around closed areas I have not an explanation.

    Hypothesis is the agitation of the film in developer is low intensity.

    George

  8. #8
    hoffy's Avatar
    Join Date
    Jan 2009
    Location
    Adelaide, Australia
    Shooter
    Multi Format
    Posts
    1,967
    Blog Entries
    1
    Images
    57
    I'm by no means an expert, but I was under the impression that you are not to use an acidic stop with Foma films? I think they recommend water only.

    Could this possibly be the cause?

  9. #9
    Rick A's Avatar
    Join Date
    Mar 2009
    Location
    north central Pa
    Shooter
    Multi Format
    Posts
    6,245
    Images
    34
    They look like air bells to me, if they were pin holes caused by acid stop they would be black spots.
    Rick A
    Argentum aevum

  10. #10

    Join Date
    Sep 2006
    Location
    UK
    Shooter
    35mm RF
    Posts
    3,550
    Quote Originally Posted by hoffy View Post
    I'm by no means an expert, but I was under the impression that you are not to use an acidic stop with Foma films? I think they recommend water only.

    Could this possibly be the cause?
    Foma's data sheet (PDF on their web site) says water or 2.0 % acetic acid stop. But could be large temperature swing and too concentrated stop but I not expect the symptoms to be either localised or look like the doughnut patterns.

    I temper accurately and use two plain water baths for stop with Foma, so your suggestion is reasonable.

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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