How Your Camera Works | Hacker News Reader

How Your Camera Works

objc.io

141 pointsadamnemecek33 comments

How your phone camera works. It's a well written article but it seems odd to cover how a camera works and leave out Aperture because of the edge case of having a fixed aperture as in a smartphone. With a longer description of aperture and some picture examples of aperture controlling DoF and exposure this would have been a complete introduction to digital photography, now it's a complete introduction to fixed-aperture digital photography...

> because of the edge case

Edge case? Phone cameras are very common and more common than DSLRs and probably more common than digital point and shoot.

True, but title is really misleading, and from true photography point of view, smart phone cameras are edge case, on low quality end of spectrum.

Also, most people with smartphone will never care for more than point & click, so suggested slight enhancement of coverage would make much more sense (although it doesn't put in anything that isn't already written out there 1000x times).

Thanks for the feedback. The reason I picked this title is simply because "your camera" for most people will be their smartphone. A bit too catchy for people with a DSLR.

But as other people have noted: Most photos today are taken with smartphones. I touch upon aperture, and linked to Wikipedia for those interested in in-depth information.

I recently started looking into computational photography. I didn't realize how much of the imaging acquisition process I was ignorant of: color theory, exposure, shutter speeds ... It's all pretty intuitive, but I feel like need to learn optics to really get it all!

There's this Stanford projects called Frankencamera [1] which is pretty jaw-dropping. They do a bunch of cool stuff but the one feature that really stood out was that you can take a photo and then focus it in post-production.

[1] https://frankencamera.wordpress.com

Post-production focus? That sounds like Lytro, another Stanford spin-off (but based on a grid of lens): https://www.lytro.com/

interesting, thanks for the link

Correct link: http://graphics.stanford.edu/projects/camera-2.0/

A few friends have done (taught) Masters degrees in photography (at a medical university, no less). A lot of time is spent painting, drawing, framing; exactly as you say, photography involves much than just pointing a camera.

I highly recommend a read through of Barbara London's Photography book [1]. Apparently this book is still commonly used for photography classes even these days.

I have the 3rd edition which is pretty old, but all of the information is still applicable - film and digital cameras share the same basic principles.

[1] http://www.amazon.com/Photography-11th-Edition-Barbara-Londo...

Here's a great article giving an even more indepth look at camera sensor technology: http://www.olympusmicro.com/primer/digitalimaging/cmosimages...

Though that only describes the Bayer array (which is used by most cameras except for Fujifilm and Sigma).

Fujifilm's mirrorless cameras use what they call X-Trans CMOS sensor tech - http://www.fujifilm.eu/uk/products/digital-cameras/interchan...

And Sigma uses the Foveon X3 CMOS sensor - http://en.wikipedia.org/wiki/Foveon_X3_sensor

I have been trying for years to make sense of how to use my digital camera. I usually just fumble around good article getting me going the right direction.

you should check out Tony Northrup on youtube. he does awesome guides to using certain model cameras (rather than just a review, an actual 'how to use your camera' guide)

Even if you dont have the camera in the video you learn so much about how they work

This is great explaining, very neat, thanks! I'll definitely link to it from time to time when friends or colleagues don't grasp the basics of capturing images and colour processing.

Thanks. Glad you liked it.

Can someone explain to me how ISO on a digital camera works? Are several pixels combined (the resolution lowered)?

I always think it's odd to have ISO settings on a digital camera.

No, the ISO setting adjusts the analog gain before conversion to digital. As you would expect, this raises the noise floor. It is natural and expected to be able to adjust speed on a digital camera, because the dynamic range of a ADC is limited, and you want to be able to use that range optimally.

For example, suppose your camera has a dynamic range of 10 stops. If you are shooting a scene with a dynamic range of 8 stops, then you get +/-1 stop of latitude where mistakes in exposure can be corrected digitally. Overexpose, and the signal will sometimes be above the range of the ADC. Underexpose, and the signal will sometimes be below the range of the ADC. You can adjust either the exposure (aperture, shutter speed) or the signal gain (ISO) to get the signal into the right range.

You do the same exact thing when you're recording digital audio: you adjust the gain so that you use most of the range of the DAC. As in photography, you can try increasing the gain afterwards, but you might get problems with noise.

Before going on a long vacation of sight-seeing I thought, I should buy a nice camera to memorialize the trip, but I don't know what to buy. Three days of research later and I figured out how the sensor type & size, shutter speed, aperture size, ISO level, and magic proprietary software combine to create a good picture in different environments. I couldn't explain it to you, but I can now find the best point-and-shoot camera for the lowest price.

I never did end up buying a camera, though.

I can't downvote, but this seems a bit thin for HN.

Noone can down vote submissions.

As far as I know most people can flag submissions so if you think it really doesn't belong here you could flag it.

Why is this page so wide?

> Click! Your camera just turned photons into bits.

Click! Your camera just made a skeuomorphic sound.

My camera has a reflex mirror and a mechanical shutter.

Reflex mirror??!? Get out. Rangefinders forever, baby! http://instagram.com/p/i35NJLQAeM/

I said to a friend once that a new camera model had improved noise reduction. He thought I meant it was quieter when taking pictures, but I actually meant the image quality was clear in low light.

Depending on the camera reduced shutter noise might be a very welcome change, too ... my old 40D is quite loud.

flat design sound effects?

IIRC due to pervs chucking cameras onto selfie-sticks and taking upskirt photos and the like, digital cameras are required to make a clear and un-muteable (camera) sound in some countries.

The word you are looking for is onomatopoeia ..

Nope. Skeuomorphism is a design concept whereby things that are in some way derived from other things retain design elements that were necessary in the original but aren't in the copy. The iOS shutter sound is an audio file played out of the device speaker, whereas it was a natural byproduct of the mechanism in the system from which the iOS camera is derived---a film camera.

Ah .. but shutter sound does support a purpose: it lets people know that a picture is being taken.

Yes; in order to qualify as a skeuomorph it doesn't need to _not_ serve a purpose, it just needs to retain design cues that were essential to the function of the original but not to the function of the copy. The iOS camera could very well do its job of taking pictures without making a shutter sound. The shutter sound is an auditory cue for the user, but not a side effect of the camera's function.

As another example, consider the iOS notes app[1] before the iOS6 design transition. The app looked like a legal pad---complete with a leather binding across the top and remnants of pages torn off. These were essential functional characteristics of the original object, but were retained in the copy only to provide visual cues to the user that remind her that the app she is using is just like a notepad.

[1] http://cdn.redmondpie.com/wp-content/uploads/2012/02/Notes-2...

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