120 film with 220 back?

Discussion in 'Medium Format' started by lane_bleess, Oct 27, 1998.

  1. I have a Pentax 645, but only a 220 back. Can I load and shoot
    120 film into it?> and what will happen?
     
  2. Lane,

    <p>

    I, too, have a Pentax 645 and love it! Anyway, to the best of my
    knowledge, the 220 film is thinner than the 120, hence the need for
    either separate backs or an adjustable back (like the Pentax 67).
    The 220 film in a 120 back would likely leave the film not 'pressed'
    completely against the back, leading to possible out of focus
    pictures. Worst case scenario would be 'wavy' pictures where parts
    were in focus and other parts out of focus.

    <p>

    Chris
     
  3. Worst case scenario: You will have to keep track of the exposures
    you make for a while, as the camera will wind up exposing the paper.

    <p>

    I have both backs, and the look identical. The presure plates feel
    identical. The load identical.

    <p>

    The only thing there are some little studs on both backs which have
    no discernable purpose. I guess they are for telling the camera what
    kind of back is there. One of these days I'll take out my multimeter
    and ohm them out just to see.

    <p>

    Go ahead and try it out. It can't jam, and you'll answer an age-old
    question equivalent of "How many licks does it take to get to the
    center of a Tootsie Roll Tootsie Pop?" :)
     
  4. I'm not familiar with the 645 film path, but the question involved
    running 120 through a 220 back. The 120 film plus paper backing will
    be a bit THICKER than 220, where you have film or paper but never both
    together. Also, on my practice roll of 220 (TXP) the film itself is
    about 0.050 inches/1.25mm narrower than the paper leader. If the
    tolerances within the film channel are tight, I can imagine that you
    might indeed jam something running thicker film/paper through it.
    Also, if the width of the channel is just right for the film only, I
    can imagine that there would be no problem putting slightly a wider
    paper leader and trailer through it alone, but that things might jam
    up on the sides when you run that wider paper through along with a
    thickness of film.

    <p>

    OTOH, unless the back is particularly delicate, it ought to be tougher
    than some film and paper, so the worst that might happen is that you
    tear up a roll of 120 finding out if it will work.

    <p>

    Let us know what you find out if you decide to try it.
     
  5. Lane,

    <p>

    I was in your position once (Bronica instead of Pentax though) and got
    conflicting answers to this question. I did try a roll of 120 (Fuji
    slide film) in my 220 back and was successful. OTOH, some responses
    I've seen stated that you may run the risk of damaging either the
    film, or less likely the back, for the reasons others have stated
    here. I didn't want to run that risk so I got a 120 back. I now have
    two 120 backs and use them both constantly. My advice is get a couple
    more back as soon as you can (I think 120 backs are most useful, but
    that's up to you). Having the ability to change your film mid-roll
    (i.e. color to B&W, or 100 to 400 ISO) and back again is one of the
    great things about these cameras. Good luck.
     
  6. Here in Germany it is not very easy to get second-hand magazines for
    the Pentax 645. A few months ago I was lucky to get a used 220 mag.
    Mostly I use 120 films and so I tried to use them in the 220 back: It
    worked, the pictures taken are of exellent sharpness. The only problem
    that occurs is that you have to watch the counter. It is possible to
    take more than 16 "pictures"...;-)
     

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