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  1. #21

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    I am not sure if this was mentioned, but PET is quite strong, which is good, unless one needs to tear a piece in the dark with no scissors at hand, or in a movie camera jam - not good for the works. Helen B pointed out the latter, which saved me some grief. Of course now I have some grief to spare. What ever happened to Helen B? She knew (knows) a lot.

    Cheers,
    Clarence

  2. #22
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    I don't think Helen Bach has posted here since 2007. In case she visits anonymously from time to time, I'd just like to emphasize that I miss her contributions, and I'm sure others do too.

    Matt

  3. #23
    AgX
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    Me too.

  4. #24

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    I can confirm, PET is more stable than cellulose acetate, does not break at low temperatures, can withstand temperatures up to 60°C and has a lower tendency to attract dust. It replaced celluose acetate for medical (X-ray) applications many years ago.

  5. #25

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    Being interested in archival properties of the B&W films that I use I only use films on a PET base.

    Several of the Rollei branded 120 and 35mm films are on a PET base. (available from Freestyle in the US.) Kodak used PET for the base of the 35mm Tech Pan but not the 120 size.

  6. #26
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    Quote Originally Posted by MattKing View Post
    I don't think Helen Bach has posted here since 2007. In case she visits anonymously from time to time, I'd just like to emphasize that I miss her contributions, and I'm sure others do too.

    Matt
    Me too Matt, that lady really knew her stuff, I've seen her post on other forums since, but I can't remember which.
    Ben

  7. #27

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    Quote Originally Posted by Phormula View Post
    I can confirm, PET is more stable than cellulose acetate, does not break at low temperatures, can withstand temperatures up to 60°C and has a lower tendency to attract dust. It replaced celluose acetate for medical (X-ray) applications many years ago.
    Certainly PET is a "Hercules" of sort.

    Harman's chairman Howard Hopwood and Simon Galley both commented on serious problems related to the use of polyester film in the imaging industry. They spoke of it's use in outter space and in the now collector's item "The Autowinder" which took a long roll of very thin polyester film.

    Howard pointed out a serious problem with this "Hercules" of a film base:

    Polyester film doesn't break and so putting polyester film in 35mm cameras
    is a very dangerous thing to do...
    if you ever get a jam it will bend your camera rather than break the film.

    Simon Galley added:

    "We got a polyester jam in a machine and it bent a six inch stainless steel roller in half...
    it will not break!"

    So yes, PET is strong!

    Perhaps as with other domesticated "pets", you might want to
    keep an eye on "the baby"!
    Last edited by Ray Rogers; 03-10-2009 at 03:31 AM. Click to view previous post history.

  8. #28
    AgX
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    So far as I know IlfordPhoto is the only manufacturer who uttered that using PET based film in 35mm cameras is dangerous.

  9. #29

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    Interesting Distractions and the Kodak's Double Negative

    Quote Originally Posted by Marco B View Post
    Hi all,

    I just stumbled upon this link, I think you will find it interesting. Also in the light of the "How film is made" thread:

    http://www.motion.kodak.com/motion/u...akes-image.pdf

    For the full reference including the other chapters of this document, go here:

    http://www.motion.kodak.com/US/en/mo...ials/index.htm

    Marco
    Hi Marco,

    Thanks for those interesting distractions!
    I briefly went through a couple of modules and came up with a few questions for anyone who wants to take a stab at them...
    I found mention in this thread and also in first link, pg.32
    (pg. 4 of 6 of the pdf) suggests piping is more serious(?) with PET film.. .

    "Film base, especially polyester, can transmit or pipe light that strikes the edge of the film and result in fog."
    This is corrected for, according to the article, by incorporating "... a neutral-density dye....

    Note the "especially polyester" part... but then the article seems to imply that less correction is needed in PET than in celluose films:
    "Dye density may vary from a barely detectable level to approximately 0.2.
    Higher levels are primarily used for halation protection in
    black-and-white negative films on cellulose bases."

    I wonder why this would be so.... ?

    They go on to mention that "Unlike fog, the gray dye doesn’t reduce the density range of an image; it adds the same density to all areas just as a neutral-density filter would. It has, therefore, a negligible eEect on picture quality."

    How is this grey dye density different from a general fog, other than perhaps being neutral and grainless?
    Just how great is the practical impact of non-neutral silver fog density on the color of the projected image?

    Is it significant at the theater level?

    Just curious...
    ---------------------------

    Also, I found this typo... well it probably is more of an authors slip...
    everyone would probably notice it so I am hesitant to mention it but just in case any one is really studying this stuff...

    MISTAKE in KODAKs PDF on Movie Film:
    Second link, Bottom of pg. 58 of original (10 of 14 in the pdf) re:sensiitometry

    The wavelengths of light, expressed in nanometers
    (nm), are plotted on the horizontal axis, and the
    corresponding diJuse spectral densities are
    plotted in the vertical axis. Ideally, a color dye
    should absorb only in its own region of the
    spectrum. However, all color dyes absorb some
    wavelengths in other regions of the spectrum. This
    unwanted absorption, which could prevent
    unsatisfactory color reproduction when the dyes
    are printed, is corrected in the film’s manufacture.

    Did you see the mistake?

    I think the last sentence should read something like:
    This unwanted absorption, which could prevent
    satisfactory color reproduction when the dyes
    are printed, is corrected in the film’s manufacture.

    Humm, there are several ways the sentence could be fixed.
    Oh well.
    Last edited by Ray Rogers; 03-10-2009 at 05:33 AM. Click to view previous post history.

  10. #30

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    Quote Originally Posted by AgX View Post
    So far as I know IlfordPhoto is the only manufacturer who uttered that using PET based film in 35mm cameras is dangerous.
    Simon notes that niether Kodak nor Foma coat consumer 35mm film on PET either.

    (I would note there may be isolated exceptions; wasn't HIE on a PET base?)

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