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  1. #1
    Graham_Martin's Avatar
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    Looking for guidance on focusing issue with Mamiya RB67 ProS

    I recently acquired this camera and it came with the No 3 Rangefinder focusing screen. When shooting landscapes I seem to be out of focus. The closer I am to the subject the more noticeable it becomes. When viewing the subject, prior to the shot, it always seems to be sharpest when the bellows are wound all the way back. Is that typical?

    Two recent images are attached. The image of the lions, shot from 8 feet away, appears to be front focused on the stonework in front of and below the lions. OTOH the one of the movie theater, shot from across the street, appears to be in focus. I use the split prism whenever there are some straight edges that I can line up.

    When I owned an RB67 in the past I almost always found that the best focus was with the bellows right up against the camera body.
    Attached Thumbnails Attached Thumbnails 25280006-LR.jpg   25280014 copy-LR.jpg  
    Graham from St. Augustine, FL

  2. #2
    MattKing's Avatar
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    Which lens are you using?
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #3

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    I couldn't really tell anything from looking at your shots. Not having owned one of these, my suggestion is generic for most any camera like yours, but the first place I would look is the WLF/focus screen. If it's been replaced and not installed correctly, that would be my first thought. Focus on something quite far away by racking the lens/bellows to infinity, then ck to see if it appears in focus on the focus screen. By the same token, grab a tape measure, measure out a distance, set the lens distance to match, and see if you have a sharp image on the focus screen.

  4. #4

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    Checking correct seating of the screen is certainly the first step. I no longer own the camera, but from what I recall, racking the bellows fully back may not guarantee infinity focus, depending on the lens. With the RZ67 that is the case. I doubt that it is possible reliably to take a distance from the scale on the side of the camera and measure out that distance on the ground, because the scale is difficult to read sufficiently accurately.

  5. #5
    Graham_Martin's Avatar
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    Quote Originally Posted by MattKing View Post
    Which lens are you using?
    65mm Sekor lens.
    Graham from St. Augustine, FL

  6. #6
    Graham_Martin's Avatar
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    I was using a 65mm lens, and I agree that reading the focus scale on the side is difficult to read. I will double check the seating of the focusing screen.
    Graham from St. Augustine, FL

  7. #7
    markbarendt's Avatar
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    As you get closer to the subject, the lens needs to move farther from the film and depth of field gets shorter.

    So in practical terms, when shooting across the street it is pretty easy to get your subjects in acceptable focus and the lens should be back darn near against the body.

    When shooting subjects that are closer it gets a little tougher, like for the lion statue but it should not be tough with the 65 mm lens, the shorter the distance from film to lens, the longer the depth of field. A 65 mm lens is pretty short.

    When you get subject distance down to say 2 feet, depth of field becomes very short and focusing can become very finicky.

    In all these cases stopping down to say f5 .6 or F8 or F11 or even F-16 can stretch out the depth of field and make focusing much easier.

    Just out of curiosity was the lion shot done on a tripod or mono pod or handheld.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  8. #8
    Graham_Martin's Avatar
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    Thanks Mark

    I was using a tripod but did not use the cable release or mirror up. On my last roll of film I used the cable release with mirror up. It will be interesting to see how much of a difference there is.
    Graham from St. Augustine, FL

  9. #9

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    Maybe it's the scans or maybe I am easily pleased but everything in the lions' shot looks to be in focus from the pool's edge all the way to the background where the "only" sign and windows look quite sharp.

    A scan of a print of the size you'd normally do might be the only way to be sure but certainly the lions' manes look quite sharp and the pic appears to have a large DoF.

    pentaxuser

  10. #10

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    Everything looks great in your posted shots.

    To check the screen you need to put a GG on the film plane as well. Open back, focus the view finder on a well lit target, check the FP GG with a loupe to see that it is as sharp as the view finder. If not you need to adjsut it.. Now focus the FP GG as sharp as can be.... yu have to decide if teh screen goes up or down to correct it.... Use the large brass screws under the screen with the spanner holes. Carefully scratch a reference line on each screw to the stationary part below so if you turn too much up or down, you can go back. ALso make sure you move each screw amt the same for all.. keeps the screen even.

    Another thing to check before doing anything.... take the lens off the camera, now look at a white wall about 3' away.... tell me if you can see the lines of the view screen nice n sharp? If not DIOPTER is the cure.
    Anyone can make a Digital print, but only a photographer can make a photograph.

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