RB67 actual image dimensions

Discussion in 'Medium Format Cameras and Accessories' started by BetterSense, Jun 2, 2011.

  1. BetterSense

    BetterSense Member

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    I don't have access to any of my RB67 negatives to measure them, but I'm trying to compare wide-angle lenses on 4x5 to their equivalents in terms of RB67 lenses. Does anyone know the length/width of the actual film gate of an RB67 back?
     
  2. Steve Smith

    Steve Smith Member

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    As luck would have it, I have an RB67 negative right here on my desk at work. The actual image size is 56mm x 69.2mm (2.21" x 2.72").


    Steve.
     
  3. Marc Akemann

    Marc Akemann Subscriber

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    56.5 mm x 68 mm (2.22" x 2.68") is what get. I measured both the film gate of my 6x7 ProS back and a recent negative.

    -Marc
     
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  4. Steve Smith

    Steve Smith Member

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    Perhaps there is some variance in the film backs then, possibly age dependent. Mine are Pro SD backs.


    Steve.
     
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    BetterSense

    BetterSense Member

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    I need a very wide lens. It looks like my 50mm RB67 lens isn't actually any wider than the 90mm I have for 4x5. Bummer. Guess need to start looking for a 24mm for 35mm.
     
  6. EdSawyer

    EdSawyer Member

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    24mm for 35mm format is basically the same as 50mm on 6x7.

    the 37mm fisheye for the RB/RZ is the widest production lens for that system.

    Mamiya developed a 43mm aspherical rectilinear lens for the RZ back in about 2002(?) I think, but never released it, sadly.

    -Ed
     
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    BetterSense

    BetterSense Member

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    The crazy this is that you can get 50mm (47 actually) lenses for 4x5, if you have like $2500 to spend. According to my calculations that would be like a 28mm lens on 6x7. I wonder how they pull that off?
     
  8. hpulley

    hpulley Member

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    The rear mask, rotating adapter and film back size and age determine the image size. The 6x8 adapter actually gives 56x76mm in portrait only. On a Polaroid or sheet film back you get a 76x76mm image (73x76mm on 3.25x4.25" Polaroid).

    A 17mm lens on 135 is hard to beat for wide angle but on my RB67 the 65mm lens seems wide enough for some reason.
     
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  9. fmajor

    fmajor Member

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    I'm not an expert by any stretch of the imagination, but by hubris i'll comment all the same. :tongue:

    Using a very scientifiic method - comparing view area to view area out of my window - to my eyes my 65mm lens on my RB67 is not nearly as wide as my 24mm f2.8 lens on my 35mm camera (Minolta XD-11). Maybe the Mamiya 50mm would add that extra bit of width to reach the 24mm - i have the manufacturers listed angle of view for these lenses (both Mamiya RB67 lenses and Minolta Rokkor lenses).

    To my eyes, the 65mm Mamiya is very, very close to the view of my Rokkor 35mm f2.8 lens.
     
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  10. David Brown

    David Brown Member

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    I agree. On a strictly anecdotal basis, I consider my RB 65mm to be = to a 35mm on 135 film, and the RB 50mm = to the 28mm on 135.

    I always think in terms of 9/5 to compare the RB67 to a 35mm camera. The "normal" lenses are 90mm and 50mm respectively. (I know, I know, there's a zillion threads about how this is wrong.) It's all an approximation anyway, since the aspect ratios are also different.

    Discuss ... :munch:
     
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    BetterSense

    BetterSense Member

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    When evaluating lens wideness, I always go by the long dimension, because to me, the most defining ability of a wide lens is how much horizon it can capture.
     
  12. michaelbsc

    michaelbsc Member

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    I tend to think about it this way too. I go so far as to consider the long dimension as my "normal" lend. A 35mm lens for 135, a 127mm for 4x5, etc.
     
  13. michaelbsc

    michaelbsc Member

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    Oh yeah, my 65mm is as close to 6x7 as I own.
     
  14. PittP

    PittP Member

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    BetterSens: What do you want to photograph, why do you need such avery wide lens?
    Basicallly agreed. Personally, I'm not so fond of the narrow wide images of cameras like xpan or the 6x17cm.
    As far as wide is concerend, the rectiliear Cosina/Voigtländer 12mm for 135 format (24x36mm) can't possibly be bet. And the Nikon mount can be adapted to virtually anything. It won't likely be your most used lens.
    In practical use, I find that 21mm (135)/ 43mm (6x7cm) cover well the field of defined seeing (not a focussed view, that would be less than the center quarter) and distortions remain "manageable", wider requires really care in composition - certainly always through an auxiliary viewfinder.
    Good light, Pitt
     
  15. Alan Gales

    Alan Gales Subscriber

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    I used to have an RZ67. You divide the focal length by 2 to get the 35mm equivalent. A 50mm on a 6x7 is like a 25mm lens on a 35mm camera.

    I owned a 25mm for my Contax and a 50mm for my RZ. When I first bought a 4x5 camera I heard that you divide by 3 to get a 35mm equivalent so I purchased a 75mm lens. I found the 75mm too wide so I sold it and bought a 90mm lens. The 90 felt like the 50mm on my RZ and the 25mm on my Contax.
     
  16. wiltw

    wiltw Subscriber

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    The official frame dimensions of the RB67 Pro-S are 56mm x 68.4mm according the Mamiya documents.

    But stop and consider that aspect ratio differences make the long dimension basis of comparison rather unequal...is it not more appropriate for all formats to compare the SHORT (vertical) dimension between formats in dealing with 'equivalent Angle of View'?!...fit that into the 8" dimension of the 8x10" print, and then it no longer matters what the 135 format captures on its negative, when it no longer fits on the print, right?

    • RB67 37mm = 0.66x short frame dimension,
      so 4x5 equivalent (assuming 93mm film holder aperture) = 61mm and 135 format equivalent = 19mm
    • RB67 50mm = 0.893x short frame dimension,
      so 4x5 equivalent (assuming 93mm film holder aperture) = 83mm, and 135 format equivalent = 21mm
    • RB67 90mm = 1.6x short frame dimension,
      so 4x5 equivalent (assuming 93mm film holder aperture) = 149mm, and 135 format equivalent = 38mm
     
    Last edited: Oct 7, 2017
  17. darkroommike

    darkroommike Subscriber

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    The widest medium format lens I am aware of is the Kowa 66 19mm, made of pure unobtanium with a plating of unicornium.
     
  18. Dan Fromm

    Dan Fromm Member

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    Hmm. Time to split hairs.

    The Kowa lens you mentioned covers a 56 mm circle. See http://www.cameramanuals.org/pdf_files/kowa_super_66.pdf. I suppose that's medium format. But it is a fisheye, not a rectilinear lens, and it doesn't cover full frame 6x6. I've never found a use for fisheyes -- others have, more power to them -- so like to think only of rectilinear lenses. There's one hair split.

    Here's another. Commonly (? gotta wonder about 617) used formats considered medium format include 6x4.5, 6x6, 6x7, 6x9, 6x12, and 6x17. The rectilinear lens with the largest angular coverage for any of these that I'm aware of is probably the 35/4.5 ApoGrandagon, which just covers 6x12. That's an honest 120 degrees.
     
  19. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    The reason they can get away with it on 4x5 is that view camera lenses don't need to deal with retrofocus designs (because they have no minimum flange-to-film-plane distance like reflex cameras do). So you can make an extreme wide-angle lens with very little distortion relatively easily for 4x5 compared to your RZ.
     
  20. Neil Grant

    Neil Grant Member

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    ...maybe 56x75mm in landscape orientation (50mm lens) -less with longer focal lengths. Even the 37mm fish eye will work with the 6x8cm back - thought the petals of the hood appear in the corners.
     
  21. Neil Grant

    Neil Grant Member

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    ...that's almost exactly how I regard them. More specifically, they are the equivalent focal lengths you suggest but with 'an extra bit on top'. These extra 'bits' are your indirect movements, and allow modest degree of image shape control - assuming partial cropping of the neg to a better print shape than 10x8in or so. Neither the 50 or 65mm are really 'wide' compared to what's possible in 35mm format. Both will work on with the 6x8 cm film back - which to my eyes is a somewhat nicer shape than 6x7 cm. Shame the vf can't show.
     
  22. Trail Images

    Trail Images Subscriber

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    RB67 37mm = 0.66x short frame dimension,
    so 4x5 equivalent (assuming 93mm film holder aperture) = 61mm and 135 format equivalent = 19mm


    I use the 37mm Fisheye on my RB ProSD a lot. I rarely tip the lens to exaggerate the distortion or give the slight Fisheye look. I find it works well for me by keeping the back completely level for landscape needs where room is tight to the subject.