Eli5: Why does a camera have to flash and time it perfectly when it takes a picture? Can’t the light just stay on?
In: 4956
Yes it’s possible but the photo will have the shadow of a flashlight instead of balanced lighting. My lenses automatically adjust to get the best picture possible so the flash will be slightly delayed.
The way I’d actually explain it to a five year old:
It can just stay on the whole time. It’s just annoying to have a light on when you’re not using it. It gets hot, it’s a waste of batteries and no one wants to stare at a light that bright all the time.
On top of everyone elses replies-
The flash is often timed and in a pattern to eliminate eye glare, or ‘redeye’.
I might be missing it but I don’t see anyone talking about the human factor. If people are adjusted to the lighting of the room they are in and a flash is needed to take a picture, the camera takes the picture before the subjects react to the intense lighting change. If the flash wasn’t directly before the picture was taken and was instead a prolonged intense light that started moments before the picture was taken, the photo would capture the subjects unintentionally squinting.
Aside from hardware, we also tend to want pictures of people, and if you’ve been staring into a bright light for 10 seconds, your pupils will be super contracted, meaning the photo will look really weird. Minimizing the duration of the flash (which is just a bright light) minimizes not only the pupil contraction in that one photo, but allows back to back photos without waiting on eyes to recover, because the stimulus isn’t long enough to warrant a consistent pupil response.
The simplified version is this:
Flash is much brighter than a “regular” light. If you had it on continuously, it would either get incredibly hot (AND be way too bright for anyone to be comfy), or it wouldn’t be as bright at the flash and wouldn’t work as well.
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