4 ms·

There's a more subtle issue with high-index plastic lenses and the new RGB LED monitors: the high dispersion of the plastic interacts badly with the red and gre

There's a more subtle issue with high-index plastic lenses and the new RGB LED monitors: the high dispersion of the plastic interacts badly with the red and green wavelengths of the RGB LED backlight, to produce a much more severe color separation effect when you're looking through a part of the lens not near the optical center. I wrote a blog post about this [0]. For the last couple of years I have been using lenses made of CR-39, the older, lower-index plastic (with a correction appropriate for computer work; that's about -5.75 diopters for my eyes), and they work much better. If your absolute correction is larger than maybe 3 or 4 diopters, and you use an RGB LED monitor, I recommend looking into this. [0] http://scottlburson2.blogspot.com/2016/01/lcd-backlights-and-eyeglass-lenses.html http://scottlburson2.blogspot.com/2016/01/lcd-backlights-and...

walterbell 9y ago
Freeform single vision lenses are marketed as having a larger optical center and less distortion for strong prescriptions, but they are expensive, https://www.2020mag.com/article/premium-free-form-single-vision https://www.2020mag.com/article/premium-free-form-single-vis... Are the CR-39 lenses noticeably thicker? Edit: first I’ve heard of wide gamut RGB LED monitors, https://pcmonitors.info/articles/the-evolution-of-led-backlights/#RGB_LED_8211_a_rare_breed https://pcmonitors.info/articles/the-evolution-of-led-backli...
- corey_moncure 9y ago
  CR-39 is great. They're scratch resistant, light, have high Abbe number (basically a measurement of the rainbow effect; higher is better), and UV opaque. I've had a pair of CR-39s in a lightweight titanium frame for over 15 years and still going strong.
- ScottBurson 9y ago
  The maximum thickness is about 4mm -- very reasonable, given the strength of the correction. This is with a fairly small round frame (lens width 41mm). The first RGB LED monitor I ran into was an Apple Cinema Display, several years ago. I initially didn't understand why I found it so uncomfortable to use. I think all the iMacs built in the last 7 years or so are RGB, as are all the Retina MacBook Pros. -- Well, as the article you linked to explains, they might be GB-r instead (green and blue LEDs with a red phosphor). From a dispersion perspective, GB-r is just as bad as RGB; so are quantum dots and the now-obsolete wide-gamut CCFL. All of these wide-gamut technologies will have much more red-green dispersion than either the old standard CCFLs or WLED. I wasn't aware of Freeform; I guess that's because I don't use progressives -- I just switch glasses, or slide them down my nose to adjust focus. But it seems to be a lens shaping technology, not a lens material.
  - walterbell 9y ago
    Hmm, does it apply to iPhone and iPad screens, especially with Apple’s “True Tone” display? Given the size of the iPhone user base, your blog post should be better known. edit: web search did not locate definitive statements about RGB LED in either iPhone or Macbook retina screens.
    - ScottBurson 9y ago
      Well, I'm not certain about past models, but the current MacBook Pro advertises "Wide color (P3)", referring to the DCI P3 gamut. This obviously requires a wide-gamut backlight of some kind. I found this [0] blog post talking about DCI P3 vs. Adobe RGB. Looks like the iPhone 7 was the first iPhone with a wide gamut [1]. No idea about the iPad. [0] http://www.colourspace.xyz/the-new-apple-imac-and-the-dci-p3-colour-gamut/ http://www.colourspace.xyz/the-new-apple-imac-and-the-dci-p3... [1] https://www.reddit.com/r/apple/comments/5287c3/lets_talk_about_that_new_display_in_iphone_7/ https://www.reddit.com/r/apple/comments/5287c3/lets_talk_abo...
  - jaggederest 9y ago
    Freeform lenses, from what I can see, are an attempt to compensate for higher-order aberration than the standard sphere, cylinder/axis, prism/base prescription
firethief 9y ago
Oh wow, I've been trying to figure out what was wrong with my subpixel hinting forever. It was right in front of my nose!

walterbell 9y ago

Freeform single vision lenses are marketed as having a larger optical center and less distortion for strong prescriptions, but they are expensive, https://www.2020mag.com/article/premium-free-form-single-vision https://www.2020mag.com/article/premium-free-form-single-vis... Are the CR-39 lenses noticeably thicker? Edit: first I’ve heard of wide gamut RGB LED monitors, https://pcmonitors.info/articles/the-evolution-of-led-backlights/#RGB_LED_8211_a_rare_breed https://pcmonitors.info/articles/the-evolution-of-led-backli...

corey_moncure 9y ago
CR-39 is great. They're scratch resistant, light, have high Abbe number (basically a measurement of the rainbow effect; higher is better), and UV opaque. I've had a pair of CR-39s in a lightweight titanium frame for over 15 years and still going strong.
ScottBurson 9y ago
The maximum thickness is about 4mm -- very reasonable, given the strength of the correction. This is with a fairly small round frame (lens width 41mm). The first RGB LED monitor I ran into was an Apple Cinema Display, several years ago. I initially didn't understand why I found it so uncomfortable to use. I think all the iMacs built in the last 7 years or so are RGB, as are all the Retina MacBook Pros. -- Well, as the article you linked to explains, they might be GB-r instead (green and blue LEDs with a red phosphor). From a dispersion perspective, GB-r is just as bad as RGB; so are quantum dots and the now-obsolete wide-gamut CCFL. All of these wide-gamut technologies will have much more red-green dispersion than either the old standard CCFLs or WLED. I wasn't aware of Freeform; I guess that's because I don't use progressives -- I just switch glasses, or slide them down my nose to adjust focus. But it seems to be a lens shaping technology, not a lens material.
- walterbell 9y ago
  Hmm, does it apply to iPhone and iPad screens, especially with Apple’s “True Tone” display? Given the size of the iPhone user base, your blog post should be better known. edit: web search did not locate definitive statements about RGB LED in either iPhone or Macbook retina screens.
  - ScottBurson 9y ago
    Well, I'm not certain about past models, but the current MacBook Pro advertises "Wide color (P3)", referring to the DCI P3 gamut. This obviously requires a wide-gamut backlight of some kind. I found this [0] blog post talking about DCI P3 vs. Adobe RGB. Looks like the iPhone 7 was the first iPhone with a wide gamut [1]. No idea about the iPad. [0] http://www.colourspace.xyz/the-new-apple-imac-and-the-dci-p3-colour-gamut/ http://www.colourspace.xyz/the-new-apple-imac-and-the-dci-p3... [1] https://www.reddit.com/r/apple/comments/5287c3/lets_talk_about_that_new_display_in_iphone_7/ https://www.reddit.com/r/apple/comments/5287c3/lets_talk_abo...
- jaggederest 9y ago
  Freeform lenses, from what I can see, are an attempt to compensate for higher-order aberration than the standard sphere, cylinder/axis, prism/base prescription

firethief 9y ago

Oh wow, I've been trying to figure out what was wrong with my subpixel hinting forever. It was right in front of my nose!