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A Pencil of Rays
Personal blog · pencilofrays.comsciencehardware
A Pencil of Rays is a personal blog at pencilofrays.com about science and hardware. Since 2022, 8 different Hacker News readers have linked it 9 times, most often “Types of optical systems in a lens designer's toolbox (2020)”. It is still writing: the last post was on 2026-09-09, and you can follow it by feed.
Too few sampled comments (5) to say how often HN recommends it.?
Why HN links it
HN readers link this newsletter for in-depth explanations of lens design, such as why smartphone lenses use complex plastic element shapes to correct aberrations, with schematics of how the systems work.
Summarised by Claude from a sample of 5 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
In optical lens design, it’s easy to fall into a single discipline, or become very good at a few subsets of lens design. Especially when you’re just starting out. Very few things beat on-the-job training for learning. If you are single-disciplined or close to it, it’s possible to feel limited or vul
Most-linked posts?
- /lens-design-forms/4 people · 4 mentions · first linked 2022-03-05
- Types of optical systems in a lens designer's toolbox (2020)3 people · 3 mentions · first linked 2022-03-05
What Hacker News says?
Hello! Original author (original tweeter?) here. This particular design is from the iPhone 7 (or, more precisely, my guess is that it's from the iPhone 7 due to both the date of the patent [1] and due to the elements matching up with marketing images of the iPhone 7), which is 6 years old now, but I think it's broadly still representative of modern smartphone lenses. In the past 5 years or so, advancements in phone…
Comment linking /lens-design-forms/
on “Modern smartphone lenses are crazy”Submitted Types of optical systems in a lens designer's toolbox (2020) as a story · 83 points
HN discussionThe picture in the tweet only shows rays originating from an object that is close to the center of the field of view. The article mentioned in another comment has better schematics: https://www.pencilofrays.com/lens-design-forms/#mobile Smartphone cameras usually have a pretty wide field of view. The complex shapes are required in order to compensate for the aberrations caused by the large angles between the optical…
Comment linking /lens-design-forms/
on “Modern smartphone lenses are crazy”Submitted Ultimate Guide to Lens Design Forms (2020) as a story · 28 points
HN discussionThe problem is an artifact of size constraints and plastic lens having far less variation in optical density, that means a lot more work to correctly direct light to avoid various types of distortion. https://www.pencilofrays.com/lens-design-forms/#mobile has a much more in depth discussion on the how and why if the lens system design (someone referenced this in a reply to the linked thread)
Comment linking /lens-design-forms/
on “Modern smartphone lenses are crazy”Submitted Types of optical systems in a lens designer's toolbox (2020) as a story · 1 points
HN discussionThe comment of Daniel Darabos points to an interesting resource, explaining how these lenses are designed: https://www.pencilofrays.com/lens-design-forms/#mobile
Comment linking /lens-design-forms/
on “Modern smartphone lenses are crazy”Not who you're replying to, but it seems this is a classic case of mistaking not noticing change is evidence of no change. I've been following this newsletter for a while as I have a passing interest in (photographic/cinematic) lens design. https://www.pencilofrays.com/
Comment linking /
on “Fluorite lenses: Corrective capabilities beyond ordinary optical glass”Found the following on sourceforge. jOcular (java8, jar file, pre-alpha but gets a couple of good reviews) https://sourceforge.net/projects/jocular/Optical Design Software for optical systems comprised of light sources, lenses, apertures, prisms, imagers, photometers, etc. Simulate light through the system and compute images and intensities at various locations in the design. Has a help page https://sourceforge.net/…
Comment linking /lens-design-forms/
on “Ask HN: Optical Lens Software?”