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Cameras and Lenses

2132 points by mariuz 6y ago

mirkodrummer 6y ago
I’m always impressed by the amount of work and quality this guy put on his posts. Especially the interactive widgets
spdebbarma 6y ago
I obviously haven't finished reading the entire post, but I wanted to simply appreciate the hard work that has gone into this. I absolutely love interactive articles. Great job!
Lwrless 6y ago
The first blog post of his that I read was Lights and Shadows (https://ciechanow.ski/lights-and-shadows/ https://ciechanow.ski/lights-and-shadows/), and wow his blog is impressive. I love it!
nodoodles 6y ago
Impressive work! Nit on design: in first ~3 attempts to scan through the page to see if it is worth reading, i found myself stopping very early when the black background started given it usually signals a footer and end of useful content. The only reason I ended up discovering there is more content was the sanity check that if it is HN front news there has to be more to it :)
- Liquid_Fire 6y ago
  Another nitpick is that the sliders are all unlabelled and rely only on their colours matching the text. I found myself having to go back and forth between the text and the sliders, and I imagine it must be worse for colour blind people.
- _def 6y ago
  Maybe this should make you think about your "worthiness" scan ;)
  - nodoodles 6y ago
    Agree it is imperfect but there is too much Internet, too little time in life, therefore fast heuristics and patterns are useful :)
mattowen_uk 6y ago
Although I knew most of technical aspect described having immersed myself in Photography several years ago, I cannot express properly how GOOD this article is. The sliders and diagrams are brilliant for helping a layperson understand how it all works. Kudos!
- echelon 6y ago
  You'd like their other work : https://ciechanow.ski/lights-and-shadows/ https://ciechanow.ski/lights-and-shadows/ https://ciechanow.ski/gears/ https://ciechanow.ski/gears/ https://ciechanow.ski/tesseract/ https://ciechanow.ski/tesseract/ Etc. Check out the whole blog! It's amazing. These are some of the most intuitive explanations coupled with the slickest animation / demo work I've ever seen. All of that put together into crystal clear educational material is such a rare gem and requires incredible talent. Impressive as hell. I hope someone is paying them to do this full time. I'd pay for this.
  - kruxigt 6y ago
    And the articles renders so fast and so smooth on my laptop. In fact they render more smoothly and loads faster than 99% of all much much less technically advanced articles out there. Wow!
    - Wistar 6y ago
      Heck, they render fast and smooth on my 3 year old iPad.
  - arendtio 6y ago
    Added the blog to my Thunderbird RSS-Feeds :-)
  - dzhiurgis 6y ago
    I was wondering why it was lighting up as visited link. Turns out it’s same blog that posted few years ago something so special it took me entire Christmas to read!
  - 6y ago
knolan 6y ago
Very impressive work, the interactive examples are excellent and will help many understand the concepts. I’m a novice when it comes to anything related to web development so I’m going to go and look at how this type of this is done. Would anyone have and suggestion or recommendations for getting started? I teach fluid mechanics with Jupyter and I use pyGEL3D for inserting 3D models but it’s far from ideal. I’ve love to do something like this.
0xfaded 6y ago
This is beautiful. I've been working with computer vision since university, but now days work underwater. I guess I should have a pretty good understanding of this stuff, but I still occasionally get caught out by optics. This is the best possible pre-reading for anyone wanting to jump into the field.
andi999 6y ago
This is really interesting. In the first picture what does the blue slider do?
- xeyownt 6y ago
  It's changing the focal length of the lens (roughly the distance between focus points of the lens). If you rotate the scene, you see the lens is blue. Further in the article, they mention the focal length, using the same coloring.
- Sillzen 6y ago
  It changes the focal length of the lens, although it does not seem to affect the lens (blue ring) in the left-hand pane which seems like a bug. There is a demonstration later in the article (below the 5th mention of "focal length") which does affect the lens (blue ring) in the left-hand pane. Rotate the scene so that you are viewing the camera side-on, and you will see the focal length of the lens changing when you move the slider.
deleted 6y ago
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strogonoff 6y ago
Lately an area of interest of mine in digital photography in particular is scene-referred vs. output-referred image formats and subjective perception. The author (justifiably) walks around this topic in his camera sensor overview, but the data captured by a sensor from photons hitting it doesn’t really contain a readily viewable image. Data values captured by a modern camera far exceed the ranges that can be reproduced by output media such as paper or screens—meaning that the only way[0] to obtain an image we can communicate to someone else (or future ourselves) as a static artifact[0] is by throwing out data and conforming values to ranges that fit in the output color space, converting scene-referred (“raw”) data to output-referred. This is where subjective perception comes in: how we perceive colors and shapes in a given scene depends a lot on what we had seen prior to this scene, our general mood, and various other aspects of our mind state. It’s only by taking control of processing scene-referred data that we can use the full range of captured values to try to convey most convincingly, within the constraints of the output space, our subjective perception of the scene around the time we pressed the shutter trigger. (Naturally, further down this rabbit hole come the questions about e.g. what our conscious perception—but not the camera—was blind to in the scene, and eventually about the nature of reality itself, at which point one may feel compelled to give up and go into painting instead.) [0] This would be quite niche, but I wonder if we could develop tools for exploring raw data at viewing stage, allowing the audience to effortlessly adjust their perception of the scene (even if within ranges specified by the photographer). Such exploration would require significant computing powers, but we’ll probably be there in a couple of years.
- strogonoff 6y ago
  To clarify, the alternative to taking control of processing scene-referred data is to use camera’s JPEG rendering of its own idea of how the scene should look.
- martomi 6y ago
  If I understand correctly, you're looking for a simplified RAW image editor? Many digital cameras allow storing RAW images alongside JPEG. The viewer can then load the RAW images into any (web-based) image viewer/editor that supports RAW format and have full control over tone mapping. The tool interface needs to be simplified to make it a better fit for the use-case you present but I don't see computing power as a bottleneck. Of course they'd still be limited by the dynamic range of the camera. This can also be resolved by calculating irradiance map based on multiple RAW images taken with different exposure times.
sebmellen 6y ago
Does Bartosz have a Patreon or something? I feel like I'm deeply indebted to him for the privilege of having read this work. Really, one of the most comprehensive and fantastic explanatory pieces I've ever read. I cannot imagine the effort that goes into writing and coding a post like this.
IndySun 6y ago
I can only echo my impressed-ness. With or without an interest in the obvious topic, it is well written, well illustrated, accurate. A superb example of the internet at its best.
hahamrfunnyguy 6y ago
I built a trinocular microscope mount for my DSLR camera out of a couple of small magnifying lenses. When I was trying to get it to work and improve the quality, I did a bunch of reading on optics. Building your own camera lens that works is pretty easy, but making it capture nice pictures is hard. Having this article back then would have been a big help! The interactive widgets are great, and it looks like they're entirely home-grown. I am really impressed with the level of detail and work that went into this post.
kepler1 6y ago
The site is the work of a guy, "him", and "his" work. We don't have to guess and say "them" and "their" work.
- franga2000 6y ago
  But it's way less effort than checking, isn't it? The name in the footer isn't English, so it's hard to know from that and there's no about page that I could find. The Twitter profile makes it more obvious, but I only clicked on it to check because of your comment. Why bother??
  - h_spacer 6y ago
    Slav surnames are gendered. * ski is male, * ska is female, * sko is neutral. Using gender neutral in this case is as insulting as calling him a dog. Other cases where using gender neutral pronouns insults everyone speaking the language is using Latinx for Latino. If you want to butcher every other languages genders like they are in English, use Latin instead - the gender neutral form of Latino in English since only the middle ages. Hope this helps.
    - smnscu 6y ago
      I'm Romanian and have many Polish friends. This is not even remotely accurate, except for basket cases that I have yet to meet.
      - h_spacer 6y ago
        https://en.wikipedia.org/wiki/Slavic_name_suffixes https://en.wikipedia.org/wiki/Slavic_name_suffixes Hope that helps.
        echelon 6y ago
        I'm still going to use they/them because a name doesn't necessarily match with one's gender.
lew89 6y ago
Amazing, just amazing. Thanks alot. I would only suggest author to set og:image in your pages. When you share it on social media no image appears, you know how does it affect spreading, right? :)
apples_oranges 6y ago
Great work, we live in amazing times! I can't imagine how humanity will evolve from now on if knowledge is as available and as well and accessibly presented as it is these days!
JosephRedfern 6y ago
What an incredible piece of work. I can only dream of having the patience, skill and drive to make something so beautiful and informative.
dandare 6y ago
It may not seem interesting at first, but I am intrigued by how they managed to draw the overlapping blades of the IRIS. > In real camera lenses an adjustable aperture is often constructed from a set of overlapping blades that constitute an iris. If you naively create 6 blades and rotate them around the pivot (the tiny screw), they will never overlap EACH OTHER. One will end up at the very top, and one at the very bottom. If you know how this was created, please let me know.
- lm28469 6y ago
  Not sure I get your question, you want to know how it works in real life ? Have a look here: https://www.youtube.com/watch?v=cR7cibDvYyo https://www.youtube.com/watch?v=cR7cibDvYyo
  - gumoro 6y ago
    I think the question is how is this drawn on a canvas. It's not trivial, if I draw 6 shapes successively, one will be on top and another at the bottom, you would not see the tip of one at the top and the other part of the same blade at the bottom. Nicely spotted, interesting question!
- minikomi 6y ago
  Do you mean, how it was drawn using canvas? I'm guessing they drew overlapped part of the last blade twice
  - gumoro 6y ago
    Looks like so, with a clever rotation, clipping, and drawing twice (had a cursory look at 'lenses.js', look for 'draw_blade')
- deleted 6y ago
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- daturkel 6y ago
  This is interesting. I don't know much about html canvas, but it looks like this is handled in the author's custom js [0] in the line that starts with: "} else if (mode === "blades") {" [0] https://ciechanow.ski/js/lenses.js https://ciechanow.ski/js/lenses.js
nothis 6y ago
I've seen a few of these kinds of interactive articles on hackernews but this is on a whole new level. Wow. One of the best explanations of just about anything I have ever seen.
- spiderfarmer 6y ago
  It's truly amazing to me how someone can be this talented. The text, the animations, the style. It's all high quality. I'm in awe.
jonplackett 6y ago
It's really fascinating - I had always assumed digital cameras had different sensors for different light colours like eyes do.
agustif 6y ago
Awesome article and blog, as an amateur photographer this is highly educational and fun to read!
lm28469 6y ago
FYI there are digital sensors which aren't using bayer filters. Some are classic sensors missing the bayer filter (leica monochrome for example) other are based on different tech like Foveon sensors [0] Many people also debayer their cameras themselves, especially in astro photography [1] [0] https://en.wikipedia.org/wiki/Foveon_X3_sensor https://en.wikipedia.org/wiki/Foveon_X3_sensor [1] https://stargazerslounge.com/topic/166334-debayering-a-dslrs-bayer-matrix/ https://stargazerslounge.com/topic/166334-debayering-a-dslrs...
- iamacyborg 6y ago
  Fuji also use what they call an X-Trans sensor. https://en.wikipedia.org/wiki/Fujifilm_X-Trans_sensor https://en.wikipedia.org/wiki/Fujifilm_X-Trans_sensor
  - thrav 6y ago
    I picked up a Fuji last Christmas, and it’s one of the best purchases I’ve made in the last decade. Their X-line takes incredible pictures, and is so approachable. If anyone has been considering more serious photography, or is having a child and wants to capture more unique shots of them, I can’t recommend them highly enough.
    - iamacyborg 6y ago
      I'm a big fan, I'm using my XT3 as a webcam right now too!
  - perardi 6y ago
    Which is still pretty much a Bayer sensor, just with a different filter layout. You still have to demosaic to get a usable file. And a well-tuned RAW convertor to do so.
    - ansgri 6y ago
      Well, it's still a CFA (color filter array), but definitely not Bayer, which is a specific class of arrangements.
The_Colonel 6y ago
I have a question for the more knowledgeable: Color filters on the sensor split the light into three wavelength ranges - red, green, blue. Then photosites measure intensity of light, which means that sensor only knows that the incoming photon is "roughly green", but doesn't actually recognize its precise wavelength. So e.g. when the light is pure orange, it falls down into red wavelength range and is counted as red. Based on this I would expect that cameras would often produce pretty incorrect colors, but they are usually pretty good (after correcting for stuff like white balance).
- schobi 6y ago
  It is just the same with your eye - and camera response curves are optimized to be similar to your eye. There is metamerism - many spectral distributions will look the same to your eye as well as to a camera. See https://en.m.wikipedia.org/wiki/Metamerism_(color) https://en.m.wikipedia.org/wiki/Metamerism_(color)
- _ph_ 6y ago
  You are right, this is a challenge. The wavelength of the light cannot be measured directly, only inferred by the intensity of the pixels with the different color filters. On the other side, most reproductions of photos are reproducing the original frequencies either. A computer screen has red, green and blue dots, which produce light at the corresponding wave lenghts. So if you have orange light, you have a signal on the green and red pixels and the green and red dots on your screen will light up. Which will be detected by the sensors for red and green light in your eyes. No where in the chain, not even in your eye, is a sensor for "orange" directly, it is just the mixture of the red and green sensitivity. It is important to note, that neither the sensor pixels nor your eyes have a complete separate reaction to a wavelength. The sensitive area strongly overlaps. So for hues of green which have rather long wavelengths, you get some reaction on the red pixels, which gets stronger as you move towards orange, where both red and green pixels detect until it gets more and more red and less green. The exact absorption curve of the sensore color filters matters here, that is one reason, different manufacturers have slightly different color rendition. On top of that is calibration, when converting the raw image into a proper RGB-image, one can further balance the response. For that, the color calibration targets are used, which have like 24 patches of different colors. Taking a phone of this target, the calibration software can both calibrate for the light illuminating the target as well as the color response of your camera. A common reason for red-green colorblindness is that the affected persons have the sensitivity between the red and green colors overlapping too strongly, so they loose the ability to differentiate. A green creates almost as strong a signal in the "red" cells. A way to improve the color vision for those people are glasses which increase that separation by absorbing the frequencies between the red and green colors.
ehejsbbejsk 6y ago
As a hobby photographer, this is simply amazing and the most intuitive article I’ve come across. This is a must read. I am curious, however, why we still can’t digitally reproduce bokeh. Apple is getting close. I thought LiDAR would theoretically solve that and could yield indistinguishable renders compared to analog lenses. That would be a game changer in my view and why I would like to see Apple develop a full-frame sensor coupled with their technology.
- barrenko 6y ago
  Not sure but - as film e.g. captures actual photons from the scene, probably some kind of information is encoded through that. Bokeh is a kind of of space representation, similar to how you can basically "see" through hearing a sound stage of instruments separated properly when someone has a really good sound system, or how dogs have "5.1/7.1" sense of smell. How does one encode that I have no idea.
  - emllnd 6y ago
    Look into light field photography tech. It is possible to capture a ”volume of light”, within which bokeh & more can be adjusted after the fact. Issue is the amount of data generated and complexity of tech versus getting a ”good enough for most situations” image via simpler means (regular photo). Regular + depth images (Apple LiDAR etc) with help of AI can create something vaguely similar to actual bokeh, but they’re missing a lot of source data. In the world of 3D rendering (content created from scratch) very advanced & realistic bokeh effects are possible, as an example see http://lentil.xyz http://lentil.xyz for the Arnold renderer.
    - samdlathsworth 6y ago
      Wow. I left the CG industry 3 years ago in a sad bout of defeat, involving both an ability to make a decent living and a realization that it would never my standards of creative engagement that were set by my lifetime love of photography and film. But, this project is very cool.
    - 6y ago
giuliomagnifico 6y ago
The article is very good but you have to consider the existence of other filters, not only the Bayer one. And the Canon Dual Pixel AF that works a bit different than the article explains https://www.canonwatch.com/dual-pixel-af-has-become-a-canon-standard-heres-how-it-works/ https://www.canonwatch.com/dual-pixel-af-has-become-a-canon-... (but the substance is the same)
- _def 6y ago
  In the article it is clearly acknowledged that there are different types. When you create a introduction like this you kind of have to limit your scope
kulesh 6y ago
This is great. Thanks for sharing.
sohkamyung 6y ago
The website sliders don't work well with a touch interface. If I use a mouse, I can smoothly move the slider values. But attempting to tap and slide them either has no response or makes the slide move to the extreme left or right. I'm using Firefox (Nightly) on a Windows 10 tablet (Microsoft Surface Go).
- notRobot 6y ago
  Sliders work perfectly for me on latest FF on latest LineageOS, which suggests that it's not a problem with the website, rather with either FF or Windows on your device.
- Mandelmus 6y ago
  It works flawlessly on my iPad in Safari.
- sohkamyung 6y ago
  I did some more testing and I think it's due to how Windows interact with the website slider. I've tried with Chrome on Windows 10 and find that the slider works but only if I touch on the line the slider is sitting on to set a value. Attempting to tap on the round circle and pulling it to slide does not work. I tried again on Firefox and if I very carefully tap on the line, I can set the slider. But touching the circle and sliding does not work. So, Firefox is more sensitive than Chrome when it comes to determining whether I am touching the line or not. I presume this is due to how Windows interprets touch events and passes them on to the browser, making the sliders hard to work with in my case.
- ddoice 6y ago
  Firefox on Android here, every animation works flawlessly.
perardi 6y ago
I’ve been an amateur photographer for over 10 years now, and I’ve never seen such an easy-to-understand but still mathematically in-depth explanation of depth of field until now. Bravo. This is excellent.
npiit 6y ago
Wow. What is this tool used to make these animations?
person_of_color 6y ago
Is it possible to make a color pinhole camera?
- MengerSponge 6y ago
  Sure! "Color" vs "Black and White" vs "Sepia" is primarily a function of the photosensitive (aka film or digital sensor) layer.
krosaen 6y ago
Looking at the page source I'm doubly impressed there seems to be no use of third party libraries. I personally happily use three.js, but still, wow. https://ciechanow.ski/js/base.js https://ciechanow.ski/js/base.js https://ciechanow.ski/js/lenses.js https://ciechanow.ski/js/lenses.js
- MetaWhirledPeas 6y ago
  I'm sure there's a simple explanation if I look at the code, but how he did the z-order for the fins on that aperture is breaking my brain.
- ddoice 6y ago
  I'm speechless, even in a mid-end android phone every animation is smooth, is like dark magic to me.
jmenter 6y ago
This article is just superb.
filleokus 6y ago
This is so good! I wonder if the author publishes the source code for the interactive bits somewhere (I could of course look at them from the presented JS, but still). I've been looking for a non-fan-inducing way to generate a DOF-effect, and the one in the first example is definitely good enough for my use case.
udev 6y ago
Brilliant work. It really helps building an intuitive foundation of these phenomena. With such intuitive foundation, one has confidence to look into the math behind the curtain, even if this math gets complex, you will still feel confident. IMO, this kind of explanations is the correct way to start teaching anything.
laithh 6y ago
Love this
simonw 6y ago
I've seen this kind of essay described as an "explorable explanation" - I absolutely love them. There's a directory of other examples of this kind of thing here: https://explorabl.es/ https://explorabl.es/
ecommerceguy 6y ago
While this is a very long article I just want to say great webpage, I'm saving this for an seo reference file.
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daralthus 6y ago
The only thing better than a pinhole camera is a pinhole camera with multiple holes. Let me explain: When you have two holes (apertures), their images would likely overlap (depending on the arrangement). Imagine you took two photos from a few millimetres apart to the left and to the right, then you superimposed them. Some areas would look ok (as both views saw the same distant object) and some would be less ok (of objects that are closer). If you have a DSLR take the lens off and put a sheet with holes in front. Just try it. Now as you add more holes you get more and more overlapping images on the same area of the sensor and eventually end up with a blur. This blur is the same blur you see with a single large hole. It's just that with a large hole you had infinitely many overlaps! Even cooler, if you happen to arrange the holes in a specific pattern you could capture images with different combinations of perspectives from different holes and you may even undo the overlaps. This is called coded aperture imaging: https://www.paulcarlisle.net/codedaperture/ https://www.paulcarlisle.net/codedaperture/ This doesn't just solve the biggest problem (limited light) of a single hole, but also captures depth information and you can use it for 3d reconstruction, refocusing etc. One final bit, with a warning of a deep rabbit hole: That "infinitely many overlaps" I was talking about happens with lenses too and is essentially a convolution where you convolve the image with itself (actually many different perspectives of itself if I am correct). Which is just the Fourier transform.
- whatshisface 6y ago
  >That "infinitely many overlaps" I was talking about happens with lenses too and is essentially a convolution where you convolve the image with itself (actually many different perspectives of itself if I am correct). Which is just the Fourier transform. That statement is a bit muddled, let me unpack it. The infinitely many overlaps thing can be expressed mathematically as the convolution of the image with a function that's one where the aperture is open, and zero where it's not. The thing about the Fourier transform is actually related to a different phenomenon. When the slit is really small, you start getting diffraction effects. The diffraction bands are approximately the Fourier transform of the slit function. However that is not significant unless the slit is extraordinarily tiny.
  - 6y ago
chandlerh 6y ago
Great article. One thing that's always stumped me as an amateur photographer is how an object is "in focus" when the rays from that object coverage to the smallest point, thus the smallest amount of pixels are getting hit. It would seem to me you would want to collect the max amount of information and thus use more of the sensor. How does converging to less of the sensor give you a sharper photo?
- snowwrestler 6y ago
  The amount of total light is the same, but the smaller the points of focus, the easier it is to distinguish image elements from each other because each point overlaps less with its neighbors. Here’s a metaphor. Let’s say you have 10 glasses, with 10 different amounts of water in them. When you hit them with a spoon, each glass makes a different musical note: 10 different notes. If you pour the water from each glass individually into 10 new glasses, you preserve those 10 notes. If you combine every two glasses into one, now you have 5 glasses, and only 5 notes. It’s the same total amount of water but you lost information.
- starky 6y ago
  If you take up a larger part of the sensor, then the distance between any two details must be larger so the areas that their light covers over the sensor don't overlap. If they overlap, you have no clue where the information is coming from. Look up circle of confusion, Rayleigh resolution criterion and sparrows resolution criterion for the technical details of resolution.
- grkvlt 6y ago
  It's more that the rays from a point on an object converge to the smallest point when in focus? The rays from the object as a whole are spread out over an object-shaped are on the image plane, unless the object is (effectively) at infinity, when they will converge to a point...
- Double_Cast 6y ago
  Ideally, the mapping from object to image is injective. What you're proposing will lead to "hash collisions" aka blurriness, since each point in the object will bleed colors into neighboring points in the image. The entire object doesn't get collapsed to a single point. Rather, a single point of the object radiates light in all directions. A lens then captures a fraction of that radiation and collapses it back down to a single point. Then we iterate over each point in the scene with a "for each".
henrikschroder 6y ago
I was 45 years old when I learned why squinting your eyes make you see sharper. Never too old to learn!
scrollbar93 6y ago
The site is really nice - Would be great if you could get rid of that horizontal scrollbar
chmaynard 6y ago
Looks like the author works at Apple: https://patents.justia.com/inventor/bartosz-ciechanowski https://patents.justia.com/inventor/bartosz-ciechanowski
colinprince 6y ago
"By default all animations are enabled, but if you find them distracting, or if you want to save power, you can globally pause all the following demonstrations." I love this writer / developer
nzealand 6y ago
In terms of sharpness, each lens is different. And the sharpness varies depending on the focal length (zoom), aperture and the sensor. A great way to visualize this, is to take a look at the sharpness of the nifty fifty canon lens https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-stm/review/ https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-s... Click into the heat map https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-stm/blur/canon-7d/ https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-s... Move the aperture from 1.8 to 2.8, and note how the sharpness increases, starting in the center of the lens. Then at about 16, diffraction kicks in and things start getting less sharp again. Things get even wilder when you introduce variable zoom and different camera bodies. It's a great way to visualize the good/fast/cheap pick two tradeoff's of lenses.
dingaling 6y ago
> Alternatively, we could increase the sensitivity of the sensor which is described using the ISO rating. Umm well, not really. The sensitivity of a digital CCD or CMOS sensor never changes; it has one 'native ISO' equivalent sensitivity and that's all. It creates the same output signal in response to a photon every time. Varying the pseudo-ISO simply varies the gain of the downstream post-readout amplifier. That's where noise is introduced. Sometimes it's better to take a deliberately underexposed photo and tweak regions of it in post to achieve the desired exposure instead of introducing global noise from in-camera amplification.
- rimliu 6y ago
  There are also "dual native ISO" sensors. Still different apmplification levels, but in this case it is before ADC. See https://www.youtube.com/watch?v=g8hHFt3ChZ8 https://www.youtube.com/watch?v=g8hHFt3ChZ8
  - formerly_proven 6y ago
    "Dual native ISO" sensors don't perform different amplification before the read out amplifier or anything like that. With an image sensor you get to decide between high sensitivity and high capacity (how much light it can detect before saturating). So a highly sensitive sensor can handle less light before clipping (which makes sense). This trade-off can be tweaked by changing the size of the photodiode (bigger diode -> more sensitive), but also electrically - simply add capacitance in parallel to the photodiode. This requires more energy, i.e. more photons, to change the voltage over the photodiode, which is what the readout measures. Dual native ISO sensors simply add another transistor (as a switch) in series to extra capacitance; this allows them to switch between low-capacitance (high sensitivity, but saturates faster) and high-capacitance (lower sensitivity, can handle more light). Edit: Haven't watched the whole video but his core explanation in there seems to be that Dual ISO means the sensors has a PGA (programmable gain amplifier) -- almost all sensors use that approach, and that's what is controlled by the ISO setting in them.
    - rimliu 6y ago
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isolli 6y ago
How is this the first time I have gained an intuitive feeling for refraction? Instead I've been taught to simply accept Snell's law. It feels very powerful that a single hypothesis - and a reasonable one at that (namely that the electrical field is continuous at the junction between materials) is enough to explain refraction!
- kazinator 6y ago
  Refraction goes beyond electrical fields. An intuitive feeling for refraction can be obtained from: - water: when waves go from, say, deeper to shallower water, their speed changes. If they are moving at an angle, refraction is seen. This can be explained by drawing wavefronts. The wavefront doesn't hit the shallower water all at the same time, and so does not slow down all at once, but gradually. - wheels: when rolling axle with two wheels goes from pavement to grass on an angle, its direction will bend direction, due to the change in speed, which is experienced by one wheel ahead of the other.
deleted 6y ago
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qwertox 6y ago
This article is stunning. The design, the way it presents the information, everything. I don't think I've ever seen such a good webpage. Edit: Now I've seen some of his other pages... This man is a genius.
m463 6y ago
this is quite a beautiful page, and in the first few seconds you can immediately grasp focus & depth-of-field/bokke. But then it keeps going!
CamperBob2 6y ago
The pinhole diameter slider is backwards; the objects should appear sharper as the aperture shrinks. Also it'd be good if you showed the effect of diminished light-gathering power at the same time, to emphasize the tradeoff. All of the sliders should be labeled. All in all, this is a good conceptual effort, but the details aren't strong.
Peteris 6y ago
Anyone else came here expecting a Haskell post?
mickcartwright 6y ago
Wow - just wow - such a great resource. This is what I love about www - exposure to such enthusiasm and expertise.
contingencies 6y ago
For a markedly less engineering oriented introduction see https://en.wikibooks.org/wiki/Modern_Photography/The_camera https://en.wikibooks.org/wiki/Modern_Photography/The_camera One interesting thing I learned recently is how they make cheap plastic lenses, and the fact that plastic lenses were invented by an Australian. They are created by choosing a polymer with good optical properties and then thermoforming it by carefully applying air pressure to raise a rounded shape to a dome after clamping the edges, then holding the air pressure constant until it has cooled. Because nothing actually touches the lens portion, optical properties are preserved.
- supernova87a 6y ago
  Do you mean, like creating a bubble of plastic fed from below where surface tension holds it in a shape like a bubble? And then letting it harden while in that shape? Does the air pressure you talk about mean blowing a stream down onto the lens? And then, no further polishing is necessary? I'm fascinated to learn more if you have a source to read more from!
  - contingencies 6y ago
    You can go up or down (probably sideways if you can account for gravity, eg. through rotary motion). Up is more common since you only need significant equipment on one side and access requirements mean that keeping the bulk of it 'down' is easier. No polishing is necessary. However, I recall reading that some polymers can be polished if you want, but IIRC it depends heavily on the polymer, the abrasive, intermediate fluids in use and result desired. Re: Source, I raided libgen for thermoforming over the last few months, visited about 10 equipment factories and studied their mechanisms and control systems, but actually learned this tidbit from 1000 Australian Inventions or some such book which I bought for my daughter before our family returned to China... to keep inventing ;)
- sudosysgen 6y ago
  This works for some lens shapes. For most though, molding is necessary.
ruminasean 6y ago
As someone who spends most of his time either shooting, teaching or hustling, this truly is phenomenal. It makes some of the more mind-bending aspects of photography perfectly clear. Great post!
deleted 6y ago
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kazinator 6y ago
If I'm conversing with a Japanese photographer in Japanese, what word do I use for "that Japanese word that American photographers use for a special kind of blur?" It can't be "bokeh" because that's just an everyday word that means blur; for instance "mae no shashin ga boketeru kara, keshimashou ka" (the previous picture is blurry, so shall I erase it?) Also, since that term came into use in around 1997, if I could have a conversation with an English-speaking photographer via time telephone to 1990, what would be the wording used?

2132 points by mariuz 6y ago

I’m always impressed by the amount of work and quality this guy put on his posts. Especially the interactive widgets

I obviously haven't finished reading the entire post, but I wanted to simply appreciate the hard work that has gone into this. I absolutely love interactive articles. Great job!

Lwrless 6y ago

The first blog post of his that I read was Lights and Shadows (https://ciechanow.ski/lights-and-shadows/ https://ciechanow.ski/lights-and-shadows/), and wow his blog is impressive. I love it!

nodoodles 6y ago

Impressive work! Nit on design: in first ~3 attempts to scan through the page to see if it is worth reading, i found myself stopping very early when the black background started given it usually signals a footer and end of useful content. The only reason I ended up discovering there is more content was the sanity check that if it is HN front news there has to be more to it :)

Liquid_Fire 6y ago
Another nitpick is that the sliders are all unlabelled and rely only on their colours matching the text. I found myself having to go back and forth between the text and the sliders, and I imagine it must be worse for colour blind people.
_def 6y ago
Maybe this should make you think about your "worthiness" scan ;)
- nodoodles 6y ago
  Agree it is imperfect but there is too much Internet, too little time in life, therefore fast heuristics and patterns are useful :)

mattowen_uk 6y ago

Although I knew most of technical aspect described having immersed myself in Photography several years ago, I cannot express properly how GOOD this article is. The sliders and diagrams are brilliant for helping a layperson understand how it all works. Kudos!

echelon 6y ago
You'd like their other work : https://ciechanow.ski/lights-and-shadows/ https://ciechanow.ski/lights-and-shadows/ https://ciechanow.ski/gears/ https://ciechanow.ski/gears/ https://ciechanow.ski/tesseract/ https://ciechanow.ski/tesseract/ Etc. Check out the whole blog! It's amazing. These are some of the most intuitive explanations coupled with the slickest animation / demo work I've ever seen. All of that put together into crystal clear educational material is such a rare gem and requires incredible talent. Impressive as hell. I hope someone is paying them to do this full time. I'd pay for this.
- kruxigt 6y ago
  And the articles renders so fast and so smooth on my laptop. In fact they render more smoothly and loads faster than 99% of all much much less technically advanced articles out there. Wow!
  - Wistar 6y ago
    Heck, they render fast and smooth on my 3 year old iPad.
- arendtio 6y ago
  Added the blog to my Thunderbird RSS-Feeds :-)
- dzhiurgis 6y ago
  I was wondering why it was lighting up as visited link. Turns out it’s same blog that posted few years ago something so special it took me entire Christmas to read!
- 6y ago

knolan 6y ago

Very impressive work, the interactive examples are excellent and will help many understand the concepts. I’m a novice when it comes to anything related to web development so I’m going to go and look at how this type of this is done. Would anyone have and suggestion or recommendations for getting started? I teach fluid mechanics with Jupyter and I use pyGEL3D for inserting 3D models but it’s far from ideal. I’ve love to do something like this.

0xfaded 6y ago

This is beautiful. I've been working with computer vision since university, but now days work underwater. I guess I should have a pretty good understanding of this stuff, but I still occasionally get caught out by optics. This is the best possible pre-reading for anyone wanting to jump into the field.

andi999 6y ago

This is really interesting. In the first picture what does the blue slider do?

xeyownt 6y ago
It's changing the focal length of the lens (roughly the distance between focus points of the lens). If you rotate the scene, you see the lens is blue. Further in the article, they mention the focal length, using the same coloring.
Sillzen 6y ago
It changes the focal length of the lens, although it does not seem to affect the lens (blue ring) in the left-hand pane which seems like a bug. There is a demonstration later in the article (below the 5th mention of "focal length") which does affect the lens (blue ring) in the left-hand pane. Rotate the scene so that you are viewing the camera side-on, and you will see the focal length of the lens changing when you move the slider.

deleted 6y ago

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strogonoff 6y ago

Lately an area of interest of mine in digital photography in particular is scene-referred vs. output-referred image formats and subjective perception. The author (justifiably) walks around this topic in his camera sensor overview, but the data captured by a sensor from photons hitting it doesn’t really contain a readily viewable image. Data values captured by a modern camera far exceed the ranges that can be reproduced by output media such as paper or screens—meaning that the only way[0] to obtain an image we can communicate to someone else (or future ourselves) as a static artifact[0] is by throwing out data and conforming values to ranges that fit in the output color space, converting scene-referred (“raw”) data to output-referred. This is where subjective perception comes in: how we perceive colors and shapes in a given scene depends a lot on what we had seen prior to this scene, our general mood, and various other aspects of our mind state. It’s only by taking control of processing scene-referred data that we can use the full range of captured values to try to convey most convincingly, within the constraints of the output space, our subjective perception of the scene around the time we pressed the shutter trigger. (Naturally, further down this rabbit hole come the questions about e.g. what our conscious perception—but not the camera—was blind to in the scene, and eventually about the nature of reality itself, at which point one may feel compelled to give up and go into painting instead.) [0] This would be quite niche, but I wonder if we could develop tools for exploring raw data at viewing stage, allowing the audience to effortlessly adjust their perception of the scene (even if within ranges specified by the photographer). Such exploration would require significant computing powers, but we’ll probably be there in a couple of years.

strogonoff 6y ago
To clarify, the alternative to taking control of processing scene-referred data is to use camera’s JPEG rendering of its own idea of how the scene should look.
martomi 6y ago
If I understand correctly, you're looking for a simplified RAW image editor? Many digital cameras allow storing RAW images alongside JPEG. The viewer can then load the RAW images into any (web-based) image viewer/editor that supports RAW format and have full control over tone mapping. The tool interface needs to be simplified to make it a better fit for the use-case you present but I don't see computing power as a bottleneck. Of course they'd still be limited by the dynamic range of the camera. This can also be resolved by calculating irradiance map based on multiple RAW images taken with different exposure times.

sebmellen 6y ago

Does Bartosz have a Patreon or something? I feel like I'm deeply indebted to him for the privilege of having read this work. Really, one of the most comprehensive and fantastic explanatory pieces I've ever read. I cannot imagine the effort that goes into writing and coding a post like this.

IndySun 6y ago

I can only echo my impressed-ness. With or without an interest in the obvious topic, it is well written, well illustrated, accurate. A superb example of the internet at its best.

hahamrfunnyguy 6y ago

I built a trinocular microscope mount for my DSLR camera out of a couple of small magnifying lenses. When I was trying to get it to work and improve the quality, I did a bunch of reading on optics. Building your own camera lens that works is pretty easy, but making it capture nice pictures is hard. Having this article back then would have been a big help! The interactive widgets are great, and it looks like they're entirely home-grown. I am really impressed with the level of detail and work that went into this post.

kepler1 6y ago

The site is the work of a guy, "him", and "his" work. We don't have to guess and say "them" and "their" work.

franga2000 6y ago
But it's way less effort than checking, isn't it? The name in the footer isn't English, so it's hard to know from that and there's no about page that I could find. The Twitter profile makes it more obvious, but I only clicked on it to check because of your comment. Why bother??
- h_spacer 6y ago
  Slav surnames are gendered. * ski is male, * ska is female, * sko is neutral. Using gender neutral in this case is as insulting as calling him a dog. Other cases where using gender neutral pronouns insults everyone speaking the language is using Latinx for Latino. If you want to butcher every other languages genders like they are in English, use Latin instead - the gender neutral form of Latino in English since only the middle ages. Hope this helps.
  - smnscu 6y ago
    I'm Romanian and have many Polish friends. This is not even remotely accurate, except for basket cases that I have yet to meet.
    - h_spacer 6y ago
      https://en.wikipedia.org/wiki/Slavic_name_suffixes https://en.wikipedia.org/wiki/Slavic_name_suffixes Hope that helps.
      - echelon 6y ago
        I'm still going to use they/them because a name doesn't necessarily match with one's gender.

lew89 6y ago

Amazing, just amazing. Thanks alot. I would only suggest author to set og:image in your pages. When you share it on social media no image appears, you know how does it affect spreading, right? :)

apples_oranges 6y ago

Great work, we live in amazing times! I can't imagine how humanity will evolve from now on if knowledge is as available and as well and accessibly presented as it is these days!

JosephRedfern 6y ago

What an incredible piece of work. I can only dream of having the patience, skill and drive to make something so beautiful and informative.

dandare 6y ago

It may not seem interesting at first, but I am intrigued by how they managed to draw the overlapping blades of the IRIS. > In real camera lenses an adjustable aperture is often constructed from a set of overlapping blades that constitute an iris. If you naively create 6 blades and rotate them around the pivot (the tiny screw), they will never overlap EACH OTHER. One will end up at the very top, and one at the very bottom. If you know how this was created, please let me know.

lm28469 6y ago
Not sure I get your question, you want to know how it works in real life ? Have a look here: https://www.youtube.com/watch?v=cR7cibDvYyo https://www.youtube.com/watch?v=cR7cibDvYyo
- gumoro 6y ago
  I think the question is how is this drawn on a canvas. It's not trivial, if I draw 6 shapes successively, one will be on top and another at the bottom, you would not see the tip of one at the top and the other part of the same blade at the bottom. Nicely spotted, interesting question!
minikomi 6y ago
Do you mean, how it was drawn using canvas? I'm guessing they drew overlapped part of the last blade twice
- gumoro 6y ago
  Looks like so, with a clever rotation, clipping, and drawing twice (had a cursory look at 'lenses.js', look for 'draw_blade')
deleted 6y ago
[deleted]
daturkel 6y ago
This is interesting. I don't know much about html canvas, but it looks like this is handled in the author's custom js [0] in the line that starts with: "} else if (mode === "blades") {" [0] https://ciechanow.ski/js/lenses.js https://ciechanow.ski/js/lenses.js

nothis 6y ago

I've seen a few of these kinds of interactive articles on hackernews but this is on a whole new level. Wow. One of the best explanations of just about anything I have ever seen.

spiderfarmer 6y ago
It's truly amazing to me how someone can be this talented. The text, the animations, the style. It's all high quality. I'm in awe.

jonplackett 6y ago

It's really fascinating - I had always assumed digital cameras had different sensors for different light colours like eyes do.

agustif 6y ago

Awesome article and blog, as an amateur photographer this is highly educational and fun to read!

lm28469 6y ago

FYI there are digital sensors which aren't using bayer filters. Some are classic sensors missing the bayer filter (leica monochrome for example) other are based on different tech like Foveon sensors [0] Many people also debayer their cameras themselves, especially in astro photography [1] [0] https://en.wikipedia.org/wiki/Foveon_X3_sensor https://en.wikipedia.org/wiki/Foveon_X3_sensor [1] https://stargazerslounge.com/topic/166334-debayering-a-dslrs-bayer-matrix/ https://stargazerslounge.com/topic/166334-debayering-a-dslrs...

iamacyborg 6y ago
Fuji also use what they call an X-Trans sensor. https://en.wikipedia.org/wiki/Fujifilm_X-Trans_sensor https://en.wikipedia.org/wiki/Fujifilm_X-Trans_sensor
- thrav 6y ago
  I picked up a Fuji last Christmas, and it’s one of the best purchases I’ve made in the last decade. Their X-line takes incredible pictures, and is so approachable. If anyone has been considering more serious photography, or is having a child and wants to capture more unique shots of them, I can’t recommend them highly enough.
  - iamacyborg 6y ago
    I'm a big fan, I'm using my XT3 as a webcam right now too!
- perardi 6y ago
  Which is still pretty much a Bayer sensor, just with a different filter layout. You still have to demosaic to get a usable file. And a well-tuned RAW convertor to do so.
  - ansgri 6y ago
    Well, it's still a CFA (color filter array), but definitely not Bayer, which is a specific class of arrangements.

The_Colonel 6y ago

I have a question for the more knowledgeable: Color filters on the sensor split the light into three wavelength ranges - red, green, blue. Then photosites measure intensity of light, which means that sensor only knows that the incoming photon is "roughly green", but doesn't actually recognize its precise wavelength. So e.g. when the light is pure orange, it falls down into red wavelength range and is counted as red. Based on this I would expect that cameras would often produce pretty incorrect colors, but they are usually pretty good (after correcting for stuff like white balance).

schobi 6y ago
It is just the same with your eye - and camera response curves are optimized to be similar to your eye. There is metamerism - many spectral distributions will look the same to your eye as well as to a camera. See https://en.m.wikipedia.org/wiki/Metamerism_(color) https://en.m.wikipedia.org/wiki/Metamerism_(color)
_ph_ 6y ago
You are right, this is a challenge. The wavelength of the light cannot be measured directly, only inferred by the intensity of the pixels with the different color filters. On the other side, most reproductions of photos are reproducing the original frequencies either. A computer screen has red, green and blue dots, which produce light at the corresponding wave lenghts. So if you have orange light, you have a signal on the green and red pixels and the green and red dots on your screen will light up. Which will be detected by the sensors for red and green light in your eyes. No where in the chain, not even in your eye, is a sensor for "orange" directly, it is just the mixture of the red and green sensitivity. It is important to note, that neither the sensor pixels nor your eyes have a complete separate reaction to a wavelength. The sensitive area strongly overlaps. So for hues of green which have rather long wavelengths, you get some reaction on the red pixels, which gets stronger as you move towards orange, where both red and green pixels detect until it gets more and more red and less green. The exact absorption curve of the sensore color filters matters here, that is one reason, different manufacturers have slightly different color rendition. On top of that is calibration, when converting the raw image into a proper RGB-image, one can further balance the response. For that, the color calibration targets are used, which have like 24 patches of different colors. Taking a phone of this target, the calibration software can both calibrate for the light illuminating the target as well as the color response of your camera. A common reason for red-green colorblindness is that the affected persons have the sensitivity between the red and green colors overlapping too strongly, so they loose the ability to differentiate. A green creates almost as strong a signal in the "red" cells. A way to improve the color vision for those people are glasses which increase that separation by absorbing the frequencies between the red and green colors.

ehejsbbejsk 6y ago

As a hobby photographer, this is simply amazing and the most intuitive article I’ve come across. This is a must read. I am curious, however, why we still can’t digitally reproduce bokeh. Apple is getting close. I thought LiDAR would theoretically solve that and could yield indistinguishable renders compared to analog lenses. That would be a game changer in my view and why I would like to see Apple develop a full-frame sensor coupled with their technology.

barrenko 6y ago
Not sure but - as film e.g. captures actual photons from the scene, probably some kind of information is encoded through that. Bokeh is a kind of of space representation, similar to how you can basically "see" through hearing a sound stage of instruments separated properly when someone has a really good sound system, or how dogs have "5.1/7.1" sense of smell. How does one encode that I have no idea.
- emllnd 6y ago
  Look into light field photography tech. It is possible to capture a ”volume of light”, within which bokeh & more can be adjusted after the fact. Issue is the amount of data generated and complexity of tech versus getting a ”good enough for most situations” image via simpler means (regular photo). Regular + depth images (Apple LiDAR etc) with help of AI can create something vaguely similar to actual bokeh, but they’re missing a lot of source data. In the world of 3D rendering (content created from scratch) very advanced & realistic bokeh effects are possible, as an example see http://lentil.xyz http://lentil.xyz for the Arnold renderer.
  - samdlathsworth 6y ago
    Wow. I left the CG industry 3 years ago in a sad bout of defeat, involving both an ability to make a decent living and a realization that it would never my standards of creative engagement that were set by my lifetime love of photography and film. But, this project is very cool.
  - 6y ago

giuliomagnifico 6y ago

The article is very good but you have to consider the existence of other filters, not only the Bayer one. And the Canon Dual Pixel AF that works a bit different than the article explains https://www.canonwatch.com/dual-pixel-af-has-become-a-canon-standard-heres-how-it-works/ https://www.canonwatch.com/dual-pixel-af-has-become-a-canon-... (but the substance is the same)

_def 6y ago
In the article it is clearly acknowledged that there are different types. When you create a introduction like this you kind of have to limit your scope

kulesh 6y ago

This is great. Thanks for sharing.

sohkamyung 6y ago

The website sliders don't work well with a touch interface. If I use a mouse, I can smoothly move the slider values. But attempting to tap and slide them either has no response or makes the slide move to the extreme left or right. I'm using Firefox (Nightly) on a Windows 10 tablet (Microsoft Surface Go).

notRobot 6y ago
Sliders work perfectly for me on latest FF on latest LineageOS, which suggests that it's not a problem with the website, rather with either FF or Windows on your device.
Mandelmus 6y ago
It works flawlessly on my iPad in Safari.
sohkamyung 6y ago
I did some more testing and I think it's due to how Windows interact with the website slider. I've tried with Chrome on Windows 10 and find that the slider works but only if I touch on the line the slider is sitting on to set a value. Attempting to tap on the round circle and pulling it to slide does not work. I tried again on Firefox and if I very carefully tap on the line, I can set the slider. But touching the circle and sliding does not work. So, Firefox is more sensitive than Chrome when it comes to determining whether I am touching the line or not. I presume this is due to how Windows interprets touch events and passes them on to the browser, making the sliders hard to work with in my case.
ddoice 6y ago
Firefox on Android here, every animation works flawlessly.

perardi 6y ago

I’ve been an amateur photographer for over 10 years now, and I’ve never seen such an easy-to-understand but still mathematically in-depth explanation of depth of field until now. Bravo. This is excellent.

npiit 6y ago

Wow. What is this tool used to make these animations?

person_of_color 6y ago

Is it possible to make a color pinhole camera?

MengerSponge 6y ago
Sure! "Color" vs "Black and White" vs "Sepia" is primarily a function of the photosensitive (aka film or digital sensor) layer.

krosaen 6y ago

Looking at the page source I'm doubly impressed there seems to be no use of third party libraries. I personally happily use three.js, but still, wow. https://ciechanow.ski/js/base.js https://ciechanow.ski/js/base.js https://ciechanow.ski/js/lenses.js https://ciechanow.ski/js/lenses.js

MetaWhirledPeas 6y ago
I'm sure there's a simple explanation if I look at the code, but how he did the z-order for the fins on that aperture is breaking my brain.
ddoice 6y ago
I'm speechless, even in a mid-end android phone every animation is smooth, is like dark magic to me.

jmenter 6y ago

This article is just superb.

filleokus 6y ago

This is so good! I wonder if the author publishes the source code for the interactive bits somewhere (I could of course look at them from the presented JS, but still). I've been looking for a non-fan-inducing way to generate a DOF-effect, and the one in the first example is definitely good enough for my use case.

udev 6y ago

Brilliant work. It really helps building an intuitive foundation of these phenomena. With such intuitive foundation, one has confidence to look into the math behind the curtain, even if this math gets complex, you will still feel confident. IMO, this kind of explanations is the correct way to start teaching anything.

laithh 6y ago

Love this

simonw 6y ago

I've seen this kind of essay described as an "explorable explanation" - I absolutely love them. There's a directory of other examples of this kind of thing here: https://explorabl.es/ https://explorabl.es/

ecommerceguy 6y ago

While this is a very long article I just want to say great webpage, I'm saving this for an seo reference file.

abcdefg911 6y ago

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- abcdefg911 6y ago
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daralthus 6y ago

The only thing better than a pinhole camera is a pinhole camera with multiple holes. Let me explain: When you have two holes (apertures), their images would likely overlap (depending on the arrangement). Imagine you took two photos from a few millimetres apart to the left and to the right, then you superimposed them. Some areas would look ok (as both views saw the same distant object) and some would be less ok (of objects that are closer). If you have a DSLR take the lens off and put a sheet with holes in front. Just try it. Now as you add more holes you get more and more overlapping images on the same area of the sensor and eventually end up with a blur. This blur is the same blur you see with a single large hole. It's just that with a large hole you had infinitely many overlaps! Even cooler, if you happen to arrange the holes in a specific pattern you could capture images with different combinations of perspectives from different holes and you may even undo the overlaps. This is called coded aperture imaging: https://www.paulcarlisle.net/codedaperture/ https://www.paulcarlisle.net/codedaperture/ This doesn't just solve the biggest problem (limited light) of a single hole, but also captures depth information and you can use it for 3d reconstruction, refocusing etc. One final bit, with a warning of a deep rabbit hole: That "infinitely many overlaps" I was talking about happens with lenses too and is essentially a convolution where you convolve the image with itself (actually many different perspectives of itself if I am correct). Which is just the Fourier transform.

whatshisface 6y ago
>That "infinitely many overlaps" I was talking about happens with lenses too and is essentially a convolution where you convolve the image with itself (actually many different perspectives of itself if I am correct). Which is just the Fourier transform. That statement is a bit muddled, let me unpack it. The infinitely many overlaps thing can be expressed mathematically as the convolution of the image with a function that's one where the aperture is open, and zero where it's not. The thing about the Fourier transform is actually related to a different phenomenon. When the slit is really small, you start getting diffraction effects. The diffraction bands are approximately the Fourier transform of the slit function. However that is not significant unless the slit is extraordinarily tiny.
- 6y ago

chandlerh 6y ago

Great article. One thing that's always stumped me as an amateur photographer is how an object is "in focus" when the rays from that object coverage to the smallest point, thus the smallest amount of pixels are getting hit. It would seem to me you would want to collect the max amount of information and thus use more of the sensor. How does converging to less of the sensor give you a sharper photo?

snowwrestler 6y ago
The amount of total light is the same, but the smaller the points of focus, the easier it is to distinguish image elements from each other because each point overlaps less with its neighbors. Here’s a metaphor. Let’s say you have 10 glasses, with 10 different amounts of water in them. When you hit them with a spoon, each glass makes a different musical note: 10 different notes. If you pour the water from each glass individually into 10 new glasses, you preserve those 10 notes. If you combine every two glasses into one, now you have 5 glasses, and only 5 notes. It’s the same total amount of water but you lost information.
starky 6y ago
If you take up a larger part of the sensor, then the distance between any two details must be larger so the areas that their light covers over the sensor don't overlap. If they overlap, you have no clue where the information is coming from. Look up circle of confusion, Rayleigh resolution criterion and sparrows resolution criterion for the technical details of resolution.
grkvlt 6y ago
It's more that the rays from a point on an object converge to the smallest point when in focus? The rays from the object as a whole are spread out over an object-shaped are on the image plane, unless the object is (effectively) at infinity, when they will converge to a point...
Double_Cast 6y ago
Ideally, the mapping from object to image is injective. What you're proposing will lead to "hash collisions" aka blurriness, since each point in the object will bleed colors into neighboring points in the image. The entire object doesn't get collapsed to a single point. Rather, a single point of the object radiates light in all directions. A lens then captures a fraction of that radiation and collapses it back down to a single point. Then we iterate over each point in the scene with a "for each".

henrikschroder 6y ago

I was 45 years old when I learned why squinting your eyes make you see sharper. Never too old to learn!

scrollbar93 6y ago

The site is really nice - Would be great if you could get rid of that horizontal scrollbar

chmaynard 6y ago

Looks like the author works at Apple: https://patents.justia.com/inventor/bartosz-ciechanowski https://patents.justia.com/inventor/bartosz-ciechanowski

colinprince 6y ago

"By default all animations are enabled, but if you find them distracting, or if you want to save power, you can globally pause all the following demonstrations." I love this writer / developer

nzealand 6y ago

In terms of sharpness, each lens is different. And the sharpness varies depending on the focal length (zoom), aperture and the sensor. A great way to visualize this, is to take a look at the sharpness of the nifty fifty canon lens https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-stm/review/ https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-s... Click into the heat map https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-stm/blur/canon-7d/ https://www.imaging-resource.com/lenses/canon/ef-50mm-f1.8-s... Move the aperture from 1.8 to 2.8, and note how the sharpness increases, starting in the center of the lens. Then at about 16, diffraction kicks in and things start getting less sharp again. Things get even wilder when you introduce variable zoom and different camera bodies. It's a great way to visualize the good/fast/cheap pick two tradeoff's of lenses.

dingaling 6y ago

> Alternatively, we could increase the sensitivity of the sensor which is described using the ISO rating. Umm well, not really. The sensitivity of a digital CCD or CMOS sensor never changes; it has one 'native ISO' equivalent sensitivity and that's all. It creates the same output signal in response to a photon every time. Varying the pseudo-ISO simply varies the gain of the downstream post-readout amplifier. That's where noise is introduced. Sometimes it's better to take a deliberately underexposed photo and tweak regions of it in post to achieve the desired exposure instead of introducing global noise from in-camera amplification.

rimliu 6y ago
There are also "dual native ISO" sensors. Still different apmplification levels, but in this case it is before ADC. See https://www.youtube.com/watch?v=g8hHFt3ChZ8 https://www.youtube.com/watch?v=g8hHFt3ChZ8
- formerly_proven 6y ago
  "Dual native ISO" sensors don't perform different amplification before the read out amplifier or anything like that. With an image sensor you get to decide between high sensitivity and high capacity (how much light it can detect before saturating). So a highly sensitive sensor can handle less light before clipping (which makes sense). This trade-off can be tweaked by changing the size of the photodiode (bigger diode -> more sensitive), but also electrically - simply add capacitance in parallel to the photodiode. This requires more energy, i.e. more photons, to change the voltage over the photodiode, which is what the readout measures. Dual native ISO sensors simply add another transistor (as a switch) in series to extra capacitance; this allows them to switch between low-capacitance (high sensitivity, but saturates faster) and high-capacitance (lower sensitivity, can handle more light). Edit: Haven't watched the whole video but his core explanation in there seems to be that Dual ISO means the sensors has a PGA (programmable gain amplifier) -- almost all sensors use that approach, and that's what is controlled by the ISO setting in them.
  - rimliu 6y ago

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isolli 6y ago

How is this the first time I have gained an intuitive feeling for refraction? Instead I've been taught to simply accept Snell's law. It feels very powerful that a single hypothesis - and a reasonable one at that (namely that the electrical field is continuous at the junction between materials) is enough to explain refraction!

kazinator 6y ago
Refraction goes beyond electrical fields. An intuitive feeling for refraction can be obtained from: - water: when waves go from, say, deeper to shallower water, their speed changes. If they are moving at an angle, refraction is seen. This can be explained by drawing wavefronts. The wavefront doesn't hit the shallower water all at the same time, and so does not slow down all at once, but gradually. - wheels: when rolling axle with two wheels goes from pavement to grass on an angle, its direction will bend direction, due to the change in speed, which is experienced by one wheel ahead of the other.

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qwertox 6y ago

This article is stunning. The design, the way it presents the information, everything. I don't think I've ever seen such a good webpage. Edit: Now I've seen some of his other pages... This man is a genius.

m463 6y ago

this is quite a beautiful page, and in the first few seconds you can immediately grasp focus & depth-of-field/bokke. But then it keeps going!

CamperBob2 6y ago

The pinhole diameter slider is backwards; the objects should appear sharper as the aperture shrinks. Also it'd be good if you showed the effect of diminished light-gathering power at the same time, to emphasize the tradeoff. All of the sliders should be labeled. All in all, this is a good conceptual effort, but the details aren't strong.

Peteris 6y ago

Anyone else came here expecting a Haskell post?

mickcartwright 6y ago

Wow - just wow - such a great resource. This is what I love about www - exposure to such enthusiasm and expertise.

contingencies 6y ago

For a markedly less engineering oriented introduction see https://en.wikibooks.org/wiki/Modern_Photography/The_camera https://en.wikibooks.org/wiki/Modern_Photography/The_camera One interesting thing I learned recently is how they make cheap plastic lenses, and the fact that plastic lenses were invented by an Australian. They are created by choosing a polymer with good optical properties and then thermoforming it by carefully applying air pressure to raise a rounded shape to a dome after clamping the edges, then holding the air pressure constant until it has cooled. Because nothing actually touches the lens portion, optical properties are preserved.

supernova87a 6y ago
Do you mean, like creating a bubble of plastic fed from below where surface tension holds it in a shape like a bubble? And then letting it harden while in that shape? Does the air pressure you talk about mean blowing a stream down onto the lens? And then, no further polishing is necessary? I'm fascinated to learn more if you have a source to read more from!
- contingencies 6y ago
  You can go up or down (probably sideways if you can account for gravity, eg. through rotary motion). Up is more common since you only need significant equipment on one side and access requirements mean that keeping the bulk of it 'down' is easier. No polishing is necessary. However, I recall reading that some polymers can be polished if you want, but IIRC it depends heavily on the polymer, the abrasive, intermediate fluids in use and result desired. Re: Source, I raided libgen for thermoforming over the last few months, visited about 10 equipment factories and studied their mechanisms and control systems, but actually learned this tidbit from 1000 Australian Inventions or some such book which I bought for my daughter before our family returned to China... to keep inventing ;)
sudosysgen 6y ago
This works for some lens shapes. For most though, molding is necessary.

ruminasean 6y ago

As someone who spends most of his time either shooting, teaching or hustling, this truly is phenomenal. It makes some of the more mind-bending aspects of photography perfectly clear. Great post!

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kazinator 6y ago

If I'm conversing with a Japanese photographer in Japanese, what word do I use for "that Japanese word that American photographers use for a special kind of blur?" It can't be "bokeh" because that's just an everyday word that means blur; for instance "mae no shashin ga boketeru kara, keshimashou ka" (the previous picture is blurry, so shall I erase it?) Also, since that term came into use in around 1997, if I could have a conversation with an English-speaking photographer via time telephone to 1990, what would be the wording used?