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Aperture focal issue

Discussion in 'Large Format Cameras and Accessories' started by caferacer75, Feb 23, 2013.

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  1. Feb 23, 2013 #1
    caferacer75

    caferacer75 Member

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    Hi Guys
    Just joined and this is my first post. I will start with a problem i am having to see if i can get any help on the matter.
    Have just completed a still life shoot on 10x8, thinking i could polaroid on 5x4 until i discovered you cant even get fuji instant anymore so i decided to go with my Rz67.
    As i was shooting in london i sent off the first two 10x8 negatives to my lab. Bizarrely i was called an hour later by my printer telling me that the focus was falling away rapidly, now this was impossible as i had shot it on f45 !! It looked more like f8/11. We eventually decided that the front lens panel was slightly out so re set it. Confidently sending off the next negatives again i got on with the job only to be told again that i was getting drop out, though one of the negs which i shot at f64 was an improvement !! I know this must be something to do with my lens but how can a lens shooting at f64 come out like f11, the lens seems mint ! I normally use this camera for landscape work, and though it has never been infinitely sharp it has performed with a greater focal wall than two inches !!
    The lens is a schneider symmar s 5.6 300mm.
    Any comments would be appreciated, and thanks for a great site, cheers tobias


    Ps luckily i backed all up on my linhof master 5x4 which is sharp as a knife.
     
  2. Feb 23, 2013 #2
    250swb

    250swb Member

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    It would be useful to know how close you were to your still life, but a DOF calculator can help you to see if the actual DOF of your 300mm lens is as much as you thought it would be. Here is one that is easy to use, in 'camera' scroll down the list until you reach 8x10 and put in the other info and your DOF will be displayed

    http://www.dofmaster.com/dofjs.html

    Steve
     
  3. Feb 23, 2013 #3
    fotch

    fotch Member

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    Hello and welcome to APUG.
     
  4. Feb 23, 2013 #4
    Jeff Kubach

    Jeff Kubach Member

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    Hello and a warm welcome to APUG!

    Jeff
     
  5. Feb 23, 2013 #5
    Worker 11811

    Worker 11811 Member

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    I don't know for sure but my guess would be something in the camera is out of alignment. Secondarily, are you sure the film is lying flat?

    I don't know how many times I have tried to readjust lenses on movie projectors only to find that the film trap was out of alignment.
     
  6. Feb 23, 2013 #6
    E. von Hoegh

    E. von Hoegh Member

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    How close were you to your still life?
     
  7. Feb 23, 2013 #7
    Prof_Pixel

    Prof_Pixel Member

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    I wonder if you are seeing the results of aperture diffraction limit effect.
     
  8. Feb 23, 2013 #8
    E. von Hoegh

    E. von Hoegh Member

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    We have insufficient information so far. He said the one at f64 (probably much smaller effective) was better (?).
     
  9. Feb 23, 2013 #9
    ic-racer

    ic-racer Member

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    You mean you negatives are over exposed? Or that you don't see any difference between between the negatives shot at f11 and f64?
     
  10. Feb 23, 2013 #10
    250swb

    250swb Member

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    I suspect what he means is that as the 300mm lens is 'standard' for 8x10 he expects the DOF to be similar to a 150mm lens on 4x5, or indeed a 45mm lens on 35mm. But the DOF is for a 300mm lens, a telephoto in smaller formats, there are no 'equivalents', the DOF will be very narrow just as the DOF of a telephoto lens is narrow.

    Steve