I don’t understand how using a flash can freeze motion better than ambient light. In the end, isn’t it all just light hitting the sensor?
I don’t understand why it would do this. I mean it’s not necessarily like the camera knows and is like “Oh they’re using flash, I’ll be nice and give them a sharper picture’. I mean obviously they don’t think like that, but all in all it’s light luminating the subject and hitting the sensor, why does something like the source of the light affect how much motion can appear in your image?
In: Technology
It’s about duration of the light. Taking an image can take time. If the subject moves while the image has a forming you get a blur.
So you want to have the film/sensor exposed to light for a very short period of time. But this introduced a new problem, you get less light with the shutter open for only an instant, and the image will be very dim.
So you need a lot of light. Taking
It in daylight is usually enough light. But otherwise you need a very well lit studio.
Enter the third option, the flash. The flash is very, very brief, and so only need to be high power and bright for a moment. So you don’t need a lot of energy you just need a little bit really fast. This means we can have small portable flashes.
Originally they were chemical reactions, small bright explosive reactions. Then they were bulbs that would actually burn out in each use. Now we have durable LEDs that last for a while.
The other detail is you have to time this brief flash for when your shutter is open.
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