Focusing RZ with RB lens?

Discussion in 'Medium Format Cameras and Accessories' started by S Raff, Apr 27, 2012.

  1. S Raff

    S Raff Member

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    Okay something I'm trying to get my head around. I understand that with the RB lenses attached and to focus at a infinity you need to open the bellows 6/7mm and that the scale on the RZ body is redundant. Is what you see on the screen then not what is projected to the film? and if not how do you achieve critical focus. Most the time I shoot with F16 and above but for those F4.5/5.6 shots how you tackle it?

    Thank you
    Stephen
     
  2. Ian C

    Ian C Member

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    With an SLR, what you see is what you get. If it looks in focus—it is in focus.
     
  3. S Raff

    S Raff Member

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    Yes true Ian, so what you are saying is.. yes you do need to make a 6/7mm adjustment for infinity but when focusing on a particular point, what you see is what you get?

    The scale on the body is still redundant though, so is there a equation that can be used to measure the focus point distance which in turn can be transfered to the focus scale on the RB lens?

    Thanks
    Stephen
     
  4. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    If I'm understanding your question correctly, just just the DOF preview. When you stop down the lens you get more depth of field on your film than what you see in the view finder. I use the DOF preview all the time.
     
  5. Kevin Kehler

    Kevin Kehler Member

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    I have noticed on my RZ that if using an RZ lens, when the bellows are fully collapsed, I am focused on infinity. When using an RB lens, I need to advance the focus a couple of mm's to get the lens to focus on infinity (i.e., then the bellows are fully collapsed, I am focused on nothing). However, what you see is what you get and as such, you should always focus on what you need to be focused. So, you might be right in that an RB lens needs a couple of mm adjustment but do not make this adjustment; look at the glass and when it is in focus there, it will be in focus on the negative.
     
  6. Ian C

    Ian C Member

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    Regarding post #3:

    See “Using RB67 Lenses on RZ PRO II Body” page 21 here:

    http://www.webster.edu/acadaffairs/asp/mediacenter/Photo/equipment manuals/Mamiya RZ67 PRO II.pdf

    The information is correct for using the RB67 lenses on all versions of RZ67 bodies.

    The FFD (flange focal distance of the RB67 body is 111mm, while the RZ67 body has FFD of 104mm. Thus an RB67 lens sits 7mm too close to the film plane to focus at infinity (or any other distance).

    Like all through-the-lens focusing systems, the SLR viewfinder image matches what you record on film. For close-up work the true bellows extension needed to determine the required exposure compensation is the reading on the bellows scale - 7mm.

    For example, at infinity focus the bellows scale reads 7mm, so the true extension is 7mm - 7mm = 0, i.e. no extension and no exposure compensation needed.

    If you close focus and the bellows scale reads, say, 32mm, then the true extension is 32mm - 7mm = 25mm and you determine exposure compensation based on 25mm of extension.

    You could still use the DOF scale with an RB lens on the RZ camera by moving the lens back 7mm towards the body after initially focusing and reading the DOF scale for that focal length. Then you’d have to refocus the lens before shooting. To do this you’d look at the bellows scale after focusing and retract the lens 7mm by the scale reading. It’s inconvenient, but can be done.

    It’s usually more practical to simply set the aperture wanted on the preset ring and close the diaphragm with the DOF lever on the right side of the lens as you view the image on the focusing screen.
     
    Last edited by a moderator: Apr 28, 2012
  7. S Raff

    S Raff Member

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    Thats great help thanks :smile:

    Stephen