Subject to lens Distance at 1:1

Discussion in 'Large Format Cameras and Accessories' started by Nikanon, Mar 15, 2011.

  1. Nikanon

    Nikanon Member

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    Hi,

    I was wondering what the ratio of subject to lens compared to lens to film distance is at 1:1? If I have any lens, in this case lets use a 210mm on a 4x5 camera, and I extend my bellows to 420mm, what distance will my subject be from my lens? My guess was it will be the same as the extension of the bellows, but how is one to figure this out?

    -Josh
     
  2. wiltw

    wiltw Subscriber

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    At 1:1, subject to focal plane = 4 * FL
     
  3. Dan Fromm

    Dan Fromm Member

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    plus inter-nodal distance.
     
  4. ic-racer

    ic-racer Member

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    In addition to above, a few more more heuristics for 1:1:
    Lens coverage is double
    Angle of view is half
    Bellows draw is double focal length
    Lens to film and lens to subject are same
    Lens is two stops slower
    Airy disks are twice as big
    Depth of field and depth of focus are the same
     
    Last edited by a moderator: Mar 16, 2011
  5. Jim Noel

    Jim Noel Member

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    A quick review indicates that all of these answers is true.
    However if you want a quick and dirty method of focusing to 1:1, both the lens to film and the lens to subject distances need to be 2x the focal length of the lens. If you measure to the middle of the shutter, you will be very close.