Accommodating of the eye

On this page I talk about normal vision: meaning: a far point of infinity (possibly using proper spectacles), photopic vision, an accommodation amplitude of 4D (around 35 years, see below graph), an average acuity of 20/15 (around 35 years),  no eye/brain deceases and for this page: using monocular vision.
When auto focussing (accommodating) the eye/brain combination needs to do at least two thinks, IMHO:
  1. a person must be able to experience that the picture is not in focus: so seeing the picture as sharp as possible in brain.
  2. the eye's lens must be able to provide focusing capabilities that matches the needed range.
    Accommodation amplitude = 1 Near point [m] - 1 Far point [m] [Dioptors]
    The accommodation amplitude of the eye depends on the age of the person. Checking several articles (Chattopadhya and Anderson) gave the below graph. The reference accommodation amplitude is defined as 4 D(iopters).
    Accomodation range depending on age

    There is a large difference between subj(ective) and obj(ective) results, certainly for persons below 30 years of age.
    The above amplitude does not say where the Far and Near points are. Using lenses/spectacles one can move these Far and Near points to the places which are normal for healthy eyes.
    And what is the Far point of 100% focussing (so without including effects due to pupil size: Depth of Field [DoF]) of the human lens?


I would like to thank the following people for their help and constructive feedback: Jim Fulton, Bill Glickman, John Krantz and all the people who provided feedback. Any remaining errors in methodology or results are my responsibility of course!!! If you want to provide constructive feedback, let me know.

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Last major content related changes: Jan. 20, 2013