Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,219   Posts: 1,532,234   Online: 835
      
Page 3 of 6 FirstFirst 123456 LastLast
Results 21 to 30 of 52
  1. #21

    Join Date
    Sep 2007
    Location
    Cambridge, UK
    Shooter
    Multi Format
    Posts
    524
    Images
    8
    Quote Originally Posted by stevewillard View Post
    So does anyone know why lead foil will not work?
    It is purely down to the kinetic energy of the particles. The largest particle accelerators (ie at CERN, and FermiLab) can generate proton energies in the region of 1 x 10e13 eV, or lead ion energies in the 1 x 10e15 eV.

    Cosmic rays start in around 1 x 10e14, and can have kinetic energies in excess of 1 x 10e20 eV. As has been said before, particles with these energies will pass through the Earth as if it is so much vacuum. Cosmic ray particles do interact with the material that they pass through, but lose so little energy (relatively speaking) that several (hundred) Earths would need to be stacked end-to-end to effectively slow down, or stop such a particle.
    Steve

    "You don't need eyes to see, you need vision" - Maxi Jazz

    Website

  2. #22

    Join Date
    Dec 2005
    Location
    Eastern, Australia
    Shooter
    Multi Format
    Posts
    1,020
    Images
    55
    g'day snal

    so? do these particles have any effect on photographic emulsions?

    Ray

  3. #23

    Join Date
    Sep 2007
    Location
    Cambridge, UK
    Shooter
    Multi Format
    Posts
    524
    Images
    8
    Quote Originally Posted by Ray Heath View Post
    g'day snal

    so? do these particles have any effect on photographic emulsions?

    Ray
    Hi Ray,

    The particles themselves, possibly, but they do not need to interact directly with the film, as when they interact with matter they create what is known as Cerenkov radiation. Cerenkov radiation is a broad spectrum electromagnetic radiation, that peaks toward the shorter (blue) wavelengths of light (actually more in the UV), and it is this that causes the cosmic ray fogging.

    The charged cosmic ray particle doesn't actually hit or disrupt atoms in the dense matter, it just interacts with the electromagnetic field of the atoms, so even interactions with the air inside storage containers can cause fogging.
    Last edited by snallan; 06-12-2008 at 07:58 AM. Click to view previous post history.
    Steve

    "You don't need eyes to see, you need vision" - Maxi Jazz

    Website

  4. #24

    Join Date
    Jun 2006
    Shooter
    Multi Format
    Posts
    187
    As far as chemical availability goes, I can't image given the Durst Lambdas and Oce LighJets that dominate the wide-format color printing market, that RA-4 chemicals will be going away any time soon.

  5. #25

    Join Date
    Feb 2005
    Location
    Fort Collins, CO 80521
    Shooter
    Large Format
    Posts
    178
    Images
    11
    I am not saying I am going to stock up now. All I am saying is that I intend to get things ready, and build a small inventory just in case things start to deteriorate. At that point I will be in a position to act decisively. My hope is that they do not deteriorate, but readyloads are being discontinued so maybe the writing is on the wall.

    I might have some test in place that will allow me to monitor the changes as my small stock of film starts to age as noted above. This will help me develop exposure strategies to compensate for the aging film. For example, if small levels of fogging start to occur from background radiation I could overexpose the film to hide/overwhelm the fogging. This would require shooting at a slower ISO. If a magenta shift starts to occur I may be able to compensate using a filter in the field to cancel it.

    One thing for sure, I am not going to be passive about it. I am going to start to explore this on a small inexpensive scale. By this fall I will have a small chest freezer that is not frostless with about 20 boxes of extra film in it. Each year I will pull one box a run suite of standardized test on it to monitor the progression of aging. Right now I am trying to come up with ideas, solutions, and strategies. I am not panicking, just being proactive. I do intend to share everything I am doing with anyone that is interested.

    So back to any ideas you may have. For example, does anyone know where I can get an inexpensive freezer alarm that goes off should the freezer break and shut off? Are there any freezers that allow you to turn off the auto-frostless feature.? Should the film be rotated periodically because of any temperature differentials in the freezer box? Is there any research or white papers about other products and long term cold storage out there that may applicable to film?

  6. #26
    keithwms's Avatar
    Join Date
    Oct 2006
    Location
    Charlottesville, Virginia
    Shooter
    Multi Format
    Posts
    6,079
    Blog Entries
    20
    Images
    129
    How about vacuum packing your film in individual packs with one of those kitchen vacuum sealers? Then if perchance you have a brown out, and you do have condensation in the freezer, it won't affect your film.
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]

  7. #27

    Join Date
    Feb 2005
    Location
    Fort Collins, CO 80521
    Shooter
    Large Format
    Posts
    178
    Images
    11
    Excelllent idea keith. I may do it in lots of 3 or 5 boxes.

  8. #28
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,972
    Images
    65
    Color films contain organic solvents to aid imaging. There was concern during space missions that these solvents would evaporate under the vacuum conditions on the moon or the low pressure conditions during the trip there and back. As it turned out, there was no problem when Kodak ran the tests, but they were for only 6 - 10 days exposure to vacuum and reduced pressure.

    IDK what would happen if you should do this in a freezer for 10 years, especially with an ambient high pressure atmosphere.

    Good luck.

    PE

  9. #29
    keithwms's Avatar
    Join Date
    Oct 2006
    Location
    Charlottesville, Virginia
    Shooter
    Multi Format
    Posts
    6,079
    Blog Entries
    20
    Images
    129
    Ron, I am not sure which organic solvents are present, but my guess is that their vapor pressures at low temps will be negligible and that outward solvent diffusion won't be an issue. I wouldn't vacuum pack a film and leave it at room temp for long term storage, but if it's stored cool... This is quite different situation than the huge temperature extremes that the early spaceraft went through several times per day... not to mention re-entry.... and the complete lack of radiation protection by the atmosphere.

    If we know what the solvents are then we can look up the vapor pressures.... If it's an issue then you can backfill with dry air to almost ambient pressure.

    Anyway, as you stay Steve, it's not like you would pack a bunch of stuff into a freezer and not touch it for ten years; on the contrary, you would be continuously using it in small batches and assessing any degradation as you go. My feeling is that there will be zero degradation in a modern, low speed (160) colour film if stored as you intend. Let's reopen this thread in ten years and see how that prediction fared! If you still have any of your film left by then, it will be worth a lot indeed!

    One final thought, if you ever have a feeling that a film that is important to you might be going off market, then for heaven's sake go ahead buy up a bunch and don't think twice- don't second guess yourself. As lucky as I was to get some polaroid materials that I did when I did, I nevertheless passed up on some opportunities to have a lot more of those films and now they are no more.... and the price for 8x10 colour polaroid is now above $50 per shot!
    Last edited by keithwms; 06-12-2008 at 08:50 PM. Click to view previous post history.
    "Only dead fish follow the stream"

    [APUG Portfolio] [APUG Blog] [Website]

  10. #30
    marsbars's Avatar
    Join Date
    Nov 2006
    Location
    Spokane Wa.
    Shooter
    35mm
    Posts
    112
    on a side note, your kitchen sealers don't create a complete vacuum. If that was so then any liquids would boil at room temperatures. They remove a great deal of the air in the bag.
    "There is something about the mystery
    of what is on a roll of film that keeps
    me shooting, none of that digital
    instant gratification for me."

Page 3 of 6 FirstFirst 123456 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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