Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Cameras and Lenses

ciechanow.ski

Post reply on HN
Print view View original

131–140 of 241 posts

Re: Cameras and Lenses

#131

Post by [deleted] »

CliffStoll wrote: post #125
whatshisface wrote: post #112

Earlier quoted context omitted.

> 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…

Indeed! We like to think of light as photons, traveling in rays in straight lines. That's geometric optics and works great for most purposes in photography. Physical optics takes into account the wave nature of light. This becomes important when the size of the lens becomes small (eg pinholes) ... there's diffraction around edges and pixels receive contributions from many points in space. Geometric optics lets you mo…

[deleted]

Re: Cameras and Lenses

#132

Post by Kye »

kepler1 wrote: post #130
echelon wrote: post #82

Earlier quoted context omitted.

Culture and gender aren't linked. Does culture tell you if someone's gender, sexual preferences, what kind of car they drive, whether or not they're a furry, what god(s) they do or do not believe in, etc.? Don't put people in boxes based on your limited world view. Think about the limit. When we're uploaded to the matrix, you'll finally be able to be whatever gender you want to be without fear for the stupid stigmas…

What a hypocrite -- feel free to let people be who they are, as long as I can force you to call them a word I want.

You opened this thread by lecturing others on the pronouns they used for the article author with no standing to do so. Who are you and why are you more authoritative on the author's pronouns than the person you attempted to correct?

Re: Cameras and Lenses

#133

Post by IshKebab »

labcomputer wrote: post #119
IshKebab wrote: post #64

Earlier quoted context omitted.

I agree, it's pretty basic but for people that don't know any of this it's an excellent explanation.

I wouldn't say it's basic at all. It's an excellent distillation of the physics of cameras. My one minor nit-pick would be introducing the wave nature of light so early--to motivate Snell's law and total internal reflection, but without discussing diffraction until well later and only in passing. Snell's law can be motivated from a purely classical particle-based model as: 1. Light travels slower through media other…

I agree I think the motivation for refraction was the weakest point - they introduced waves, and even showed that the waves have to be continuous at the boundary... and then... back to rays!

It just needs a diagram showing the waves refracting, and the geometry of the wave fronts. (Pretty annoying that they never explained refraction like that in school either - Snell's law was just a given when it's actually really trivial to derive from first principles.)

Re: Cameras and Lenses

#134

Post by davidkuhta »

ehejsbbejsk wrote: post #38

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-fram…

Sidenote, it appears the author works for Apple.

Re: Cameras and Lenses

#135

Post by echelon »

kepler1 wrote: post #130
echelon wrote: post #82

Earlier quoted context omitted.

Culture and gender aren't linked. Does culture tell you if someone's gender, sexual preferences, what kind of car they drive, whether or not they're a furry, what god(s) they do or do not believe in, etc.? Don't put people in boxes based on your limited world view. Think about the limit. When we're uploaded to the matrix, you'll finally be able to be whatever gender you want to be without fear for the stupid stigmas…

What a hypocrite -- feel free to let people be who they are, as long as I can force you to call them a word I want.

To be clear, I never forced you to do anything. You just got angry at me.

Re: Cameras and Lenses

#137

Post by thinkloop »

ehejsbbejsk wrote: post #38

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-fram…

Phone cameras are extremely wide-angle so everything is in focus and there is no natural bokeh. To add bokeh, you have to separate the subject from the background, and then also determine how far different parts of the background are. This requires very advanced AI for non-trivial images (see the imperfections in Photoshop's "select subject" tool), which Apple is actually still doing (that's what portrait mode is). But if it's not perfect, it quickly becomes worthless, so in short, they are doing it, but only the most advanced companies can try.

Re: Cameras and Lenses

#138

Post by echelon »

kepler1 wrote: post #129
echelon wrote: post #79

Earlier quoted context omitted.

> The site is the work of a guy, "him", and "his" work. We don't have to guess and say "them" and "their" work. Assumptions are presumptuous and harmful. Everyone is a they/them until otherwise stated. These are extremely useful pronouns. You're a they/them. Calm down. You seem to be overly attached to regressive labels. I don't know what drives this in you, but the universe is burning and people just want to be happ…

I'll share something with you. The level of consideration you have for people who are no more than 1% of the population is admirable. Very admirable, in comparison with the actual large problems that I'm sure you pay 0% attention to each day, and do make assumptions about. So very admirable that you go out of your way to bring this to the level of everyone having to select a pronoun in their dropdown menu because you…

You're lashing out in anger. Calm yourself.

It seems like you dislike trans folk. I'm not sure what they did to hurt you, but I suspect your fears and hate are the result of conditioning.

What harm is it to use singular "they"?

It avoids assumptions. It also avoids sexism. Do you want a world where all contributions are assumed to come from men?

You've got a lot of fear and anger. Reflect on it. Let it go.

I don't know if you're a Christian, but even if you aren't, remember that Jesus said to love one another first. It's one of the most important messages for the world. Love, not hate and fear.

Re: Cameras and Lenses

#139

Post by snowwrestler »

chandlerh wrote: post #113

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?

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.

Re: Cameras and Lenses

#140

Post by adolph »

CliffStoll wrote: post #125
whatshisface wrote: post #112

Earlier quoted context omitted.

> 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…

Indeed! We like to think of light as photons, traveling in rays in straight lines. That's geometric optics and works great for most purposes in photography. Physical optics takes into account the wave nature of light. This becomes important when the size of the lens becomes small (eg pinholes) ... there's diffraction around edges and pixels receive contributions from many points in space. Geometric optics lets you mo…

Thanks for weighing in. My kid and I are really enjoying The CuCoo's Egg!
Post reply on HN