Seedling
Exposure Triangle
#camera#photography#exposure#basics
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Brightness in a photo or video is determined by the product of three variables.
Change any one and exposure changes. Which is why you always think of the three together.
All three can be expressed in a shared unit: the stop.
1 stop = light doubled or halved
| Variable | Example of a 1-stop change |
|---|---|
| Aperture | f/2.8 → f/4 (one stop narrower, half the light) |
| Shutter speed | 1/60 → 1/125 (half the time, half the light) |
| ISO | 800 → 400 (half the gain, effectively half the light) |
Stop down aperture by 1, then either lengthen shutter by 1 stop or raise ISO by 1 stop, and exposure stays the same. That's the whole game.
Each one changes one more thing besides brightness. That's where the trade-off lives.
| Variable | Side effect | Direction |
|---|---|---|
| Aperture | Depth of field | Wider opening → shallower DoF (blurred bg) |
| Shutter speed | Motion blur | Longer shutter → more streaking |
| ISO | Noise / grain | Higher ISO → more noise |
Setting exposure is the act of deciding which of the three side effects to give up.