DoF dependent subject distance bracketing - Feature Requests - CHDK Forum

DoF dependent subject distance bracketing

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Offline fudgey

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DoF dependent subject distance bracketing
« on: 13 / October / 2008, 18:32:53 »
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Currently our continuous mode focus bracketing is a bit cumbersome, because the +, -, +/- by integer multiplies of a constant value type of bracketing (which works marvelously for Tv bracketing) don't suit focus distance well.

This is because depth of field increases when focus distance increases. So, to cover the entire focus range in one bracketing series, one must take very densely separated shots at close distance (a few cm apart at the finest), but near Infinity there's no such need and a short step will result in a ridiculously high number of shots.

Subject distance bracketing should be (at least as an option) tied to the depth of field.

PROPOSAL:
      Add new parameter to subject distance bracketing to select Increment type: metric/DoF.
      In the new DoF mode:
          - If bracketing type is '+': Next subject distance is equal to current far limit.
          - If bracketing type is '-': Next subject distance is equal to current near limit.
          - If bracketing type is '+/-':
            shot 1: original subj.distance
            shot 2: far limit of shot 1
            shot 3: near limit of shot 1
            shot 4: far limit of shot 2
            shot 5: near limit of shot 3
            shot 6: far limit of shot 4
            shot 7: near limit of shot 5
            i.e.: First shot uses original subject distance and second shot uses its far limit,
            odd shots after the first shot use near limit the previous odd shot
            and even shots after the second shot use far limit of the previous even shot

          - we could also introduce an additional multiplier parameter to the near/far limit.
            "1" would mean what I described above. A value less than zero would result in a
            finer step (more shots to cover the entire focus range) and vice versa (probably
            leaving some depths blurry).


 

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