Mamiya RB Pro-SD with 6x8 power back - cropping line question

Discussion in 'Medium Format Cameras and Accessories' started by tkamiya, Aug 4, 2012.

  1. tkamiya

    tkamiya Member

    Messages:
    4,252
    Joined:
    Oct 3, 2009
    Location:
    Central Flor
    Shooter:
    Multi Format
    I just bought a Mamiya RB Pro-SD with a 6x8 power back.

    Looking through WLF, I see the normal guide lines for vertical orientation.

    Here's the question. As I understand it, these guidelines are for 6x7 film back. I have a 6x8 back. How do I know where my real guideline is for this back??

    I am aware, I get full 6x8 on vertical position only.
     
  2. tkamiya

    tkamiya Member

    Messages:
    4,252
    Joined:
    Oct 3, 2009
    Location:
    Central Flor
    Shooter:
    Multi Format
    Found my own answer.... TYPE-A focusing screen.
     
  3. tkamiya

    tkamiya Member

    Messages:
    4,252
    Joined:
    Oct 3, 2009
    Location:
    Central Flor
    Shooter:
    Multi Format
    Hum....

    According to this site http://rb67.helluin.org/accessories/

    There is a type A and there is a type A for 6x8. How does this work? I have what appears to be a type A that came with my Pro-SD. But my back is 6x8 power back. So... what do I do??
     
  4. CGW

    CGW Member

    Messages:
    2,797
    Joined:
    Apr 19, 2010
    Shooter:
    Medium Format
    Wasn't there a viewfinder mask for 6x8 that shipped with the 6x8 motorized back?
     
  5. MattKing

    MattKing Subscriber

    Messages:
    16,816
    Joined:
    Apr 24, 2005
    Location:
    Delta, BC, Canada
    Shooter:
    Multi Format
    I've got a really incomplete understanding of this, but here goes ....

    As I under stand this, you need to have a Pro-SD, a later Pro-S or a modified early Pro-S or modified Pro body to obtain a 6x8 image on your film.

    None of the viewfinder screens will show the entire image - the viewing system isn't quite big enough. The movable guide lines are, however accurate, because they show where the short side edges (the 56mm dimension) are. What isn't shown accurately is where the ends of the long dimensions are - the viewfinder isn't big enough.

    I surmise that the special 6x8 version of the A screen is slightly longer in the vertical dimension.

    Have you seen this photo-net thread, with included chart?: http://photo.net/medium-format-photography-forum/00Y50b
     
  6. tkamiya

    tkamiya Member

    Messages:
    4,252
    Joined:
    Oct 3, 2009
    Location:
    Central Flor
    Shooter:
    Multi Format
    So... there IS another type-A screen (why did they name it the same!) for 6x8.... Thank you for the pointer.
     
  7. MattKing

    MattKing Subscriber

    Messages:
    16,816
    Joined:
    Apr 24, 2005
    Location:
    Delta, BC, Canada
    Shooter:
    Multi Format
    I think that Type A actually refers only to the type of screen (all matte with fresnel).

    It is just that it comes in two slightly different layouts.