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You for sure don't want glass lenses. Your biggest issue isn't poly, it's your lens thickness. Best way to get the thinnest lenses possible is to use round fram

by alar44 5y ago

You for sure don't want glass lenses. Your biggest issue isn't poly, it's your lens thickness. Best way to get the thinnest lenses possible is to use round frames. Perfect circles would be ideal, rectanglish in any way is going to thicken them significantly. Mention those issues to your eye doctor too, they'll know how to reduce abberation with different lens designs if that's something that bothers you.

frosted-flakes 5y ago
It's not the lens thickness, it's the optical density (Abbe number). Different lens materials have different Abbe numbers. (I first learned of this here on HN: https://news.ycombinator.com/item?id=19315650 https://news.ycombinator.com/item?id=19315650)
- alar44 5y ago
  I know, I work in the optical industry. Abbe value is one part of it, but thickness is the multiplier. For most prescriptions, you'll never notice. But with a high negative, you have thicker lenses. If you use something with a lower index, they get even thicker. So what you do is use high index material to thin it as much as possible, then use round frames to prevent the lenses from flaring on the sides.
  - frosted-flakes 5y ago
    For a given lens strength (prescription), the material with the highest Abbe number will have the fewest chromatic aberrations. Is that not correct, and the whole point of the Abbe number? Some higher-index materials have noticeably worse Abbe numbers than others, and for my prescription of -9.75/-8.75 I selected a high-index 1.61 lens because it supposedly had an Abbe number of 41 whereas the higher index (and thinner) 1.67 or 1.74 lenses have much worse Abbe numbers of 32 and 33. Sure, the lenses are thick, but that doesn't bother me, and neither do chromatic aberrations much anymore. Also, smaller lenses may reduce chromatic aberrations, but only because they reduce the field of view. I would rather have clear side vision with some aberrations than have very blurry side vision.
    - alar44 5y ago
      Yes that's the point of an Abbe value but if your lenses are super thin you can't tell. Chromatic abberation becomes more apparent as the lens thickness increases. Glass has the lowest but it's irrelevant if you're making glass an inch thick for example. No matter what you use, you'll have very noticeable abberation. The tradeoff for a thicker lens using 1.53 vs 1.74 will never be worth it as you'll be wearing coke bottles and you'll still see abberation because it's so damn thick.
    - deleted 5y ago
      [deleted]

by alar44 5y ago

frosted-flakes 5y ago

It's not the lens thickness, it's the optical density (Abbe number). Different lens materials have different Abbe numbers. (I first learned of this here on HN: https://news.ycombinator.com/item?id=19315650 https://news.ycombinator.com/item?id=19315650)

alar44 5y ago
I know, I work in the optical industry. Abbe value is one part of it, but thickness is the multiplier. For most prescriptions, you'll never notice. But with a high negative, you have thicker lenses. If you use something with a lower index, they get even thicker. So what you do is use high index material to thin it as much as possible, then use round frames to prevent the lenses from flaring on the sides.
- frosted-flakes 5y ago
  For a given lens strength (prescription), the material with the highest Abbe number will have the fewest chromatic aberrations. Is that not correct, and the whole point of the Abbe number? Some higher-index materials have noticeably worse Abbe numbers than others, and for my prescription of -9.75/-8.75 I selected a high-index 1.61 lens because it supposedly had an Abbe number of 41 whereas the higher index (and thinner) 1.67 or 1.74 lenses have much worse Abbe numbers of 32 and 33. Sure, the lenses are thick, but that doesn't bother me, and neither do chromatic aberrations much anymore. Also, smaller lenses may reduce chromatic aberrations, but only because they reduce the field of view. I would rather have clear side vision with some aberrations than have very blurry side vision.
  - alar44 5y ago
    Yes that's the point of an Abbe value but if your lenses are super thin you can't tell. Chromatic abberation becomes more apparent as the lens thickness increases. Glass has the lowest but it's irrelevant if you're making glass an inch thick for example. No matter what you use, you'll have very noticeable abberation. The tradeoff for a thicker lens using 1.53 vs 1.74 will never be worth it as you'll be wearing coke bottles and you'll still see abberation because it's so damn thick.
  - deleted 5y ago
    [deleted]