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    Is my vision that bad? No, it's just a bug in Apple's Calculator

    (martin.wojtczyk.de)
    631 points wojtczyk | 14 comments | 31 Aug 24 04:29 UTC | HN request time: 0s | source | bottom
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    dylan-m ◴[31 Aug 24 05:51 UTC] No.41406819[source]▶
    One of my favourite unreported MacOS issues comes from how, at some point, they changed the appearance of the window close button to be a particular shade of red with a tiny little X in the center. And if you happen to be using a particular kind of screen and possibly wearing glasses, that little X kind of wanders around in the button, appearing just slightly off center in a maddening way. Made only more maddening by the glasses component: https://www.robbert.org/2014/10/the-off-center-close-button/.

    That post points out it’s probably just subpixel stuff causing the issue, but I think my thick, cheap glasses at the time were adding a layer of chromatic aberration to something that was already visually confusing.

    I assume it’s kind of gone away at this point with all the high DPI screens these days. But I remember thinking at the time, if there was a public bug tracker, that issue would be a fun one.

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    1. mrob ◴[31 Aug 24 06:52 UTC] No.41406994[source]▶
    >More expensive lenses have a coating to compensate for this chromatic aberration.

    You can't compensate for chromatic aberration with a coating. You need a compound lens made from multiple elements each with a different dispersion, e.g.:

    https://en.wikipedia.org/wiki/Achromatic_lens

    More expensive glasses lenses usually have worse chromatic aberration than cheap ones. The cheapest material for glasses lenses (PADC, often called by the brand name CR-39) has one of the best Abbe numbers (measure of dispersion).

    https://en.wikipedia.org/wiki/CR-39

    https://en.wikipedia.org/wiki/Abbe_number

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    2. kortilla ◴[31 Aug 24 08:23 UTC] No.41407335[source]▶
    Can you link to something to buy?
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    3. mrob ◴[31 Aug 24 08:42 UTC] No.41407408[source]▶
    I don't think anybody makes achromatic glasses lenses because they would be too thick and heavy.

    AFAIK, every optician sells PADC (e.g. CR-39) lenses.

    4. w4rh4wk5 ◴[31 Aug 24 09:18 UTC] No.41407534[source]▶
    I can confirm this. I had annoyingly bad chromatic aberration with my previous glasses. I specifically asked for CR-39 lenses for my next set of glasses and now it's barely noticeable at all.

    I would recommend this to any programmer who uses high-contrast syntax highlighting. To me, it felt fatiguing every time I noticed differently colored words scrolling slight further than other words on a terminal screen on the same line.

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    5. azlev ◴[31 Aug 24 10:12 UTC] No.41407735[source]▶
    TIL. Thank you.
    6. agent86 ◴[31 Aug 24 10:12 UTC] No.41407736[source]▶
    One thing to keep in mind is that CR-39 is not impact resistant. They will shatter and can do horrible things to your eyes when they do. Kids should always be put in impact resistant lenses.

    If you’re a desk jockey, or impact resistance is not a concern, CR-39 will give the least aberration with the exception of crown glass.

    The hidden hack here if you need/want impact resistance is to ask for Trivex lenses. Same impact resistance as polycarbonate but much better ABBE value. It’s often overlooked because it costs a little more than polycarbonate and most people don’t complain about the distortion.

    Also, anecdotally, you get what you pay for with progressive lenses. I have a cheap lens in my sunglasses and a higher end lens in my daily drivers and I can easily tell the difference.

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    7. jrockway ◴[31 Aug 24 10:20 UTC] No.41407764[source]▶
    This really bothered me many years ago, and I tried CR-39 and even glass, just for fun. I was never that happy with the results. I could always distract myself with chromatic aberration, and I think I eventually decided not to care anymore.

    But right now, I have high index lenses and am reading HN with Dark Reader, and even if I use the maximum strength of my glasses (progressive bifocals), I can't really see any chromatic aberration.

    I'm not sure if I should be happy or worried.

    8. germinalphrase ◴[31 Aug 24 11:24 UTC] No.41408026[source]▶
    I can’t speak to glasses, but limiting chromatic aberration in the binocular world does seem to involve coatings (at least as Swarovski, Leica, Zeiss present it).
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    9. 4gotunameagain ◴[31 Aug 24 11:38 UTC] No.41408101[source]▶
    If you cut some wavelengths, you won't get their contribution to the distortions ;)
    10. sitharus ◴[31 Aug 24 11:39 UTC] No.41408106[source]▶
    You can’t eliminate chromatic aberration with coatings, it’s a physical property of how the lens interacts with light. The only way to fix it is to adjust your lens types or materials. Zeiss’ current marketing seems to agree https://www.zeiss.com/consumer-products/us/nature-observatio...

    Coatings are still very useful to reduce other lens artefacts though.

    11. xattt ◴[31 Aug 24 12:30 UTC] No.41408408{3}[source]▶
    > It’s often overlooked because it costs a little more than polycarbonate and most people don’t complain about the distortion.

    I just started wearing glasses. I asked about fringing and they had brushed my concerns off as me being new to glasses.

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    12. cubefox ◴[31 Aug 24 14:50 UTC] No.41409285[source]▶
    I thought I got used to the color fringes in my glasses, but the real problem is that they actually reduce image clarity away from the center of the lenses. If you look e.g. at white text on a dark background from an angle, the chromatic aberration blurs (the color components of) the letters together. You can't really see clearly by moving the eyes to the edge of the FoV of your glasses; you have to turn your head instead.

    This is directly contradicting the main purpose of glasses: to see clearly. So it's actually somewhat less safe to e.g. drive with glasses that have major chromatic aberration. No idea why optometrists brush it off as a minor glitch.

    13. kps ◴[31 Aug 24 15:06 UTC] No.41409404[source]▶
    For those with stronger prescriptions who want higher index lenses to reduce thickness (and weight), look at http://opticampus.opti.vision/tools/materials.php and/or talk to your optician about available materials. (Personally, I've settled on MR-8 for my last couple pairs of computer glasses.)
    14. w4rh4wk5 ◴[31 Aug 24 16:55 UTC] No.41410150{4}[source]▶
    Deal with it for a few weeks, your brain will likely adapt.