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Thread: Higher the index, higher the chromatic aberration at the edges?

  1. #1
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    Higher the index, higher the chromatic aberration at the edges?

    I'm not aware of the physics but I've had a few patients complain to me after switching to higher index CR-39s (sometimes even 1.57) that they are liking the better look but when driving, the straight lines seldom stay straight, especially near the edges.

    Is this an inherent problem with high index lenses? That is, for the same diopter, is the Chromatic Aberration directly proportional to the lens' index?

    Or is this due to some specific process during the making of such lenses (AR, etc.) that can be avoided by giving an appropriate instruction to the lab to skip that process?

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    Master OptiBoarder optical24/7's Avatar
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    SV, Bi's or PAL's? Could be the inherent nature of hi-index lenses: they tend to use flatter B.C.'s. Also, many of the SV hi-index lenses use an aspheric front. You need to specify an OC hight along with mono PD's. On higher powers, a low abbe could affect off axis viewing because of LCA. (lateral chromatic aberration)

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    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    Higher index *usually* means lower abbe, which = higher dispersion/more lateral color.

    B
    Last edited by Barry Santini; 08-09-2012 at 06:52 PM.

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    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    A great informative read by a Carl Zeiss lens designer and fellow Optiboarder Darryl Meister-

    http://www.opticampus.com/cecourse.p...ic_aberration/

    From the same web site this may explain why straight lines curve with new lenses. Scroll down to the Base Curve section-

    http://www.opticampus.com/cecourse.php?url=lens_design/
    Last edited by Uncle Fester; 08-09-2012 at 02:59 PM.

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    Master OptiBoarder MakeOptics's Avatar
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    deleted
    Last edited by MakeOptics; 08-09-2012 at 06:12 PM.

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