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Thread: Freeform SV - quantifying the improvement

  1. #51
    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
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    DRK for the grand slam!
    I sit here wondering how my organization would skyrocket w/DRK as our chief……..
    I bend light. That is what I do.

  2. #52
    What's up? drk's Avatar
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    Hey! Thanks!

  3. #53
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Ok, here’s the science behind the statements and observations I’ve made:


    1. Axial chromatism is real in the human eye. The optical system of the eye consists of nearly homogenous refracting media of similar index of refraction. This, along with it’s short focal length, is the why behind the eye’s color error.
    2. This axial color error—and resultant defocus effect—is ever present in the eye’s retinal image.
    3. The reason we humans do not observe this axial color error is that evolution has “filtered” it out in our visual processing, no doubt in order to improve “optics.”
    4. Even sharp-eyed emmetropic individuals do not report seeing color—even when viewing the edge of a quarter moon on a cloudless night. In such high contrast conditions as these, one should see the color error of the eye. But we don’t.
    5. The small angular field subtense seen by the fovea/foveola reduces the likelihood that the eye’s transverse color error will also be observed.
    6. But…the color error of a lens—whether it be via low abbe, high power, or both—absolutely will contribute, in combination with the eye’s inherent error, to further degradation of the retinal image…whether an individual reports rainbowing around an object or not.
    7. In a moderate to stronger hyperopic presbyope, the reading image is impacted by a combination of both the distance from the actual OC and the greater refractive power presented by the reading add. Myopes are the opposite.
    8. This applies also to segmented lenses.


    I mentioned I uncovered this by accident, while sherlocking unsatisfactory vision in a +7.00/2.50add segmented hyperope. The vision with their new 1.67 aspheric FT’s was unclear in the reading zone, but not their previous 1.60 FTs. I tried them both on and saw the color fringing and the less clear image for myself. Thus began the journey to better understand the why.


    As a profession—and I include myself here—we seem to alternately place one foot in the arena of the importance of pure optics, while simultaneously placing the other in the arena of 20/Happy in order to conveniently explain why we feel pure optics doesn't matter in the real world of patient’s vision and reported complaints. I think it’s important to keep trying to achieve a mastery and understanding of both.


    Barry
    Last edited by Barry Santini; 01-04-2022 at 07:12 PM.

  4. #54
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    Excellent addition to this topic, as usual, Sir! Thanks for always making a difference!

    Happy New Year, old friend!

  5. #55
    One eye sees, the other feels. OptiBoard Silver Supporter
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    Quote Originally Posted by Barry Santini View Post
    Hyperopic presby Rxs are far more impacted by the off axis effects of low abbe than myopic Rxs.
    Yes. When looking through a spectacle lens hyperopic eyes must rotate to a greater degree too see objects located away from the primary gaze due to magnification (move closer towards your monitor and notice the reduced apparent field of view) and image displacement towards the apex from prismatic effects, and is true for all angles of gaze, although most important in multifocal design (corridor length and width). The induced prism (Prentice's rule) causes the off-axis blur (see TCA or Transverse Chromatic Aberration).

    Quote Originally Posted by drk View Post
    1. A very low number of people reject eyeglasses for chromatic aberration.
    True, especially when all of the aberrations are addressed and minimized. Get them wrong, and there is your dagger.

    Best regards,

    Robert Martellaro
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    Science is a way of trying not to fool yourself. - Richard P. Feynman

    Experience is the hardest teacher. She gives the test before the lesson.



  6. #56
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    Quote Originally Posted by Uncle Fester View Post
    The thread name seems lacking for a Hall of Fame thread.
    While the original thread name will appear any suggestions for a short but succinct line or two of what this discussion is talking about besides Quantifying FF SV?
    Wasn't talking about this thread, was talking about the ones Robert posted.

    Quote Originally Posted by Robert Martellaro View Post
    Lensman,

    There are two types of chromatic aberration: Lateral or transverse, and axial or longitudinal. See...

    https://www.optiboard.com/forums/sho...ll=1#post44885

    And...

    https://www.optiboard.com/forums/sho...ll=1#post45680

    Best regards,

    Robert Martellaro

  7. #57
    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    I'll defer to the Selection Committee as I believe Dom DiMaggio and Dave Concepcion belong in Copperstown.

  8. #58
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    Quote Originally Posted by Uncle Fester View Post
    I'll defer to the Selection Committee as I believe Dom DiMaggio and Dave Concepcion belong in Copperstown.
    We can't talk about any of this 'til after Dickie Moegle's funeral.

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