[HN Gopher] Cameras and Lenses (2020)
___________________________________________________________________
Cameras and Lenses (2020)
Author : sebg
Score : 302 points
Date : 2026-01-01 17:18 UTC (5 hours ago)
(HTM) web link (ciechanow.ski)
(TXT) w3m dump (ciechanow.ski)
| Fiveplus wrote:
| Every time I come across one of Bartosz posts, I drop everything
| to read it. And I learn so much.
|
| The way he builds up the mental model from a simple photon bucket
| to a pinhole and finally to a lens system is just incredible. I
| particularly loved the section on the circle of confusion. I've
| read dozens of explanations on depth of field, but being able to
| interactively drag the aperture slider and see exactly how the
| cone of light narrows and the blur reduces makes it click in a
| way that static text never could. This really should be the
| standard for digital textbooks.
| Y_Y wrote:
| Amazing as usual.
|
| I am always on the lookout for the classic sin of making it look
| like electromagnetic waves wiggle in space like a snake. I know
| it's convenient to glue the tangent space to the underlying
| physical space, but I think it confuses students.
|
| To be clear: the amplitude of the electric and magnetic fields
| (and hence their components in each direction) oscillate in
| space/time. Any particular wave though should travel in a
| straight line (usual caveats apply). Of course you may
| incidentally also get e.g. sinusoidal variations in intesity
| perpendicular to the wavevector, but that will be because of the
| overall beam characteristics.
|
| I don't mean to say I know a better way to show this, and I am
| aware of many complicating factors. I just think lots of people
| (my former students and self included) can come away with a wrong
| idea about how these waves work.
| mal10c wrote:
| I agree with your thought process. Factoring in antenna type
| and reflections also causes difficulties when explaining
| concepts like super position. The sinusoid is a good
| illustration of what a given receiver might detect at some
| location (X,Y,Z). A more accurate way to show that may be a
| light source fading on and off to match some frequency (below
| THz). Then factoring in the speed of light, at time zero, the
| light will be off, at some arbitrary time 1, the light will be
| illuminated at 0.25 (scale goes up to 1 here). The light energy
| peak at time 1 is at the light. Then at time 2, the light goes
| up to 0.5. That means that the 0.25 light is now 1 unit away
| from the light while the 0.5 is at the light. Step to time 3
| and the light goes up to 0.75, meaning 1 unit from the light,
| the light is at 0.5 and 2 units from the light, the light is
| dimmer at 0.25. This repeats with the light hitting 1.0 then
| falling back to 0.75, then 0.5, etc. The movement of light is
| key and I think that's what is often either misunderstood or
| just not considered enough.
| behnamoh wrote:
| Can we donate to creative individuals like the OP so they keep
| making amazing stuff? This is the kind of output LLMs will not be
| able to produce any time soon.
| macintux wrote:
| He has a Patreon: https://www.patreon.com/ciechanowski
| sho_hn wrote:
| "Make a Bartosz-style website about $topic" seems like a fun
| benchmark idea. Maybe more so than pelicans on bicycles.
|
| To be honest, though, this seems like ideal content for an LLM
| to produce. It's basically fact regurgitation.
| andyfilms1 wrote:
| Doesn't seem to work in Firefox. :(
| uhoh-itsmaciek wrote:
| FF on Android seems to work fine here. What problem are you
| seeing?
| mcdonje wrote:
| Works fine for me with Firefox on Debian. Are you sure you
| don't have an extension breaking it?
| compiler-guy wrote:
| Working fine on Firefox for IOS.
| cfraenkel wrote:
| Also works in Firefox (144.0.2) / MacOS (10.15)
| fsckboy wrote:
| I use firefox with javascript mostly off (UMatrix) but when I
| turned it on for fonts.googleapis.com the site and sliders all
| seem to worke. then I turned it on for gstatic.com
| fonts.gstatic.com , and not sure if that changed anything else.
| I'm on linux desktop
| dang wrote:
| One past thread (only?) - others?
|
| _Cameras and Lenses_ -
| https://news.ycombinator.com/item?id=25357315 - Dec 2020 (213
| comments)
| ChrisArchitect wrote:
| (2020)
|
| Some discussion then:
| https://news.ycombinator.com/item?id=25357315
| stared wrote:
| I am amazed by people like Bartosz Ciechanowski and Andrey
| Karpathy. What would be a lifetime side project for other smart
| and curious people, they seem to release every quarter. How do
| they do it?
|
| Most people who are smart and creative are nowhere near as
| productive. And most people who are extremely productive don't
| get sidetracked by side projects.
| _jayhack_ wrote:
| Great article. For another fantastic explainer on optics, see
| 3Blue1Brown's video on refraction:
| https://www.youtube.com/watch?v=KTzGBJPuJwM
| fsckboy wrote:
| > Pictures have Art has _always been a meaningful part of the
| human experience. From the first cave drawings, to sketches and
| paintings, to modern photography, we've mastered the art of
| recording what we_ see think and feel.
| Sharlin wrote:
| Your "correction" does not make sense. "Pictures" and "art" are
| overlapping categories but neither is a subset of the other.
| Pictures in and of themselves are plenty fascinating to humans,
| without bringing art into the equation.
| fsckboy wrote:
| it is your critique that does not make sense. I was not
| applying any hierarchy or subsetting whatsoever. Inseparable
| unity would be closer to the point.
|
| I was making the point that the cave painters believed
| everything including rocks and trees were deeply invested
| with spiritual power, and they didn't draw a cave painting
| without investing it with spiritual ideas. Even if one of
| their goals was to capture an accurate image of some animals,
| and indicate when in the lunar or solar cycle they were
| expected to calve, when they went hunting for one a part of
| the goal would be cut out its heart and eat it raw because of
| the power contained within, and give thanks to the great
| mother. Inseparable.
|
| even though I am not spiritual at all, I find your worldview
| too barren to explain human endeavor.
| fsckboy wrote:
| Cameras and Lenses and photography has been such a fascinating
| and open and do-it-yourself tinkering medium for well over a
| century: when are we going to get to be able to play around with
| what's inside iPhone, Samsung, and Pixel cameras?
|
| (maybe we already can, I'm simply asking)
| scosman wrote:
| If anyone hasn't already seen Bartosz's mechanical watch
| animations, they are also amazing:
| https://ciechanow.ski/mechanical-watch/
| nntwozz wrote:
| Bartosz Ciechanowski's blog brings back the joy of surfing the
| web during the heyday of Adobe Flash (minus the 100% CPU).
|
| It's so much fun manipulating things, exploring and getting
| surprising feedback.
|
| I know it's not really fair to compare this highly scientific
| masterpiece to the artistic flash websites of the past, but for
| me at least it immediately evokes the same feelings.
| zbendefy wrote:
| Tangential, but Flash had a nice side effect that the "app"
| could be exported in a self contained way via SWF.
|
| Exporting this site for example in a future proof way is not
| that obvious. (Exporting as pdf wont work with the webgl
| applets, exporting the html page might work but is error prone
| depending in the website structure)
|
| 50 years from now, flash emulators will still work on swf
| files, but these sites might be lost. Or is there a way to
| archive sites like this?
| plagiarist wrote:
| What a fantastic article!
|
| Makes me wish for a similar resource that would teach 3+ element
| optics, moving elements, and sortof get closer to modern lens
| design.
| brcmthrowaway wrote:
| Does anyone know of a lens that can make a laser look like a
| spotlight?
| aj7 wrote:
| Look up "beam expanding telescope."
| pontussw wrote:
| This is so incredibly well done
___________________________________________________________________
(page generated 2026-01-01 23:00 UTC)