Light,
captured.
From a hole in a wall to the four cameras in your pocket.
- 01From dark box to darkroom · how light becomes a picture
- 02Objective & body · lens, focal length, shutter
- 03Light is everything · exposure and its trade-offs
- 04Is it a "real" photo?
- 05Your phone · then we go shoot
A dark box and a hole
Light travels in straight lines. Light from the top of the tree can only pass the hole downward, so the image lands upside down.
Big hole: bright but blurry. Tiny hole: sharp but dark, and then blurry again from diffraction. A lens solves both.
Both just count photons
Film: silver halide crystals of random size and position. A hit crystal turns to black silver in the developer, so you get a negative.
Sensor: a regular grid of light buckets under red, green and blue filters. Software guesses the two missing colours per pixel.
A sensor is colour-blind. And size matters.
Bayer filter. Each pixel only sees red, green or blue. Half are green, because our eyes are most sensitive to green. The camera fills in the rest.
Big vs small. A full-frame camera sensor next to a tiny one. A bigger sensor collects far more light in the same exposure. That's why a system camera beats a phone in the dark.
From negative to print
The film leaves the camera with an invisible image. Chemistry makes it visible; a second exposure turns the negative into a print.
- Develop the filmtotal darkness · ~8 min
- Enlargerlight through the negative · ~10 s
- Developerthe picture appears · ~1–2 min
- Stop bathhalts developing · ~30 s
- Fixermakes it light-safe · ~3 min
- Wash & dry~10 min wash, then hang
The first photographs took hours, then minutes
1827 · ~8 hours or more
Niépce coats a pewter plate with bitumen, which hardens where light hits it. The view from his window.
1838 · several minutes
Daguerre's silver plate. The busy street looks empty because traffic moved too fast to register. Bottom left: a man stood still long enough to get his boots shined.
"You press the button, we do the rest"
1888 · Kodak No. 1. $25 with film for 100 shots. When the roll was full you mailed the whole camera back, and Kodak sent prints and a reloaded camera.
Inside: a roll of film, one lens, one fixed shutter speed. No focusing at all.
1975 · Kodak again. Steven Sasson's prototype: 100 × 100 pixels, 3.6 kg, 23 seconds to save one photo to a cassette tape. Kodak didn't sell it.
Exposure time went from a working day to a blink
A lens bends every ray back to one point
Focusing means moving the lens until that point lands exactly on the film or sensor.
Close the aperture and the blur circle shrinks. That is why a small aperture gives more of the scene in focus.
Same spot, different lens
Skate filmers get right next to the trick and still fit everything in. Watch Sour Solution II ↗
What each setting costs you
Shutter speed. The same scene, shutter open for longer and longer. Short freezes the motion. Long smears it, but lets in more light.
ISO. Same shells, darker light each time: 1 s at ISO 200, 1/30 s at ISO 5000, then 1/140 s at max. Faster shutter, more noise.
Aperture. Wide open, only the chestnut is sharp. The background melts into bokeh.
Not enough light? Something has to give.
Is a digital photo less "real" than film?
Go shoot. Upload to the gallery.
- 01Bokeh
Get close to your subject, keep lights far behind it. Shoot once with portrait mode and once without. - 02Ultra-wide
Switch to 0.5×. Get low and very close so the near thing looks huge. - 03Zoomed in
Max optical zoom on a detail across the room. See how the background squashes.
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Take as many as you like in each category, whenever you have the chance. The link keeps working, so you can keep adding photos.
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Browse on your phone too. Tap a photo to see the camera settings it used.