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  1. #21

    Join Date
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    The only differece between 120 n 220 film is the backing paper. The film itself is exactly the same stuff for both!

    The film plane is exactly the same for both 120 n 220 backs... otherwise you would never focus a sharp image if you changed backs. The viewfinder is adjusted to match the focal plane of the film, no matter if it is 120 or 220. They both have to agree agree to a sharp image. If you were to have different focal planes for 120 vs 220 one will always be out of focus when changing backs in a shoot. DaHa?

    The preasure plates are the same in 120 n 220 backs as are the springs and tensioners. Parts from one can be used in the other but not the counters or the metering mechanisms.

    The real differnce in build are the counters n frame metering mechanisms. The 220 mechanism takes into account winding less, no paper, on the take up spool thus metering the frame length differently, by increasing the roll's diameter on the take up using 120 in a 220 back you may have to do some experimenting to see how the spacings fall.

    Run a 120 test roll through the 220 back n mark where the frames align?
    Anyone can make a Digital print, but only a photographer can make a photograph.

  2. #22
    ic-racer's Avatar
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    Quote Originally Posted by MFstooges View Post
    Sorry, I was just using your words. Plate is slightly forward when not attached to camera body. When the back attached to the body then the film plane on both backs will be in the same distance from lens flange. Like I said no difference except for the more pressure that is meant to compensate zero point zero xxxwhatever milimetres.
    Again each camera and back will have its own issues when using the wrong film. I don't want to imply what you have observed on your cameras is wrong (especially if you are referring to the Hassleblad, which has a film gate a little different than just about every other MF camera).
    As an example, some cameras (Rolleiflex TLRs and Yashica 124G) put the pressure plate farther back from the outer rails on the "120" setting. For example if you look closely you will see the indentation in the pressure plate where it touches the outer film rails and allows the pressure plate (which of course is a misnomer in that it puts no direct pressure on the film in these cameras) to sit closer to the lens.

    Other cameras, like the Rollieflex SLXs, have a fixed film gate depth regardless of the 120 or 220 setting on the film back.

    My opinion is that it probably does not make much difference (ie different pressure plate location for 120 and 220) because the film can be wavy and not perfectly flat in the film gate to a much larger amount than the small distance representing the thickness of the paper.
    Last edited by ic-racer; 09-18-2012 at 05:06 PM. Click to view previous post history.

  3. #23

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    Jun 2010
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    Always late to the party, but it should also be noted that the leaders are different between 120 and 220 film:


    220 film leader:

    Length of paper = 22.25"
    Start mark to film = 7.5"

    There's about an inch and a half of unexposed film past the paper, so I'm going to try 8.5" for my start mark to film.

    120 paper :

    Head to film start: 15-1/2" (from full width paper)
    Start Arrow to film: 7"

    The tail leaders are different too, but it doesn't matter .

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