Amount of light and exposure

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  • #215161

      Ok, a stupid question…

      A difference of 1 stop means that the amount of light entering the camera is halved or doubled, according to what element of the exposure triangle is modified.
      But does it work both ways? I mean, if the amount of lights in a scene is doubled or halved, does it translate in a stop difference (so for example i’d obtain the same exposure if i’d double the light instead of increasing 1 step in the ISO) ? I did some very simple and basic test with a light metering app and they suggest me that it’s what light  does.

      I realize that it’s a bit naive question , ah ah! but finding the link between the amount of light and the exposure is an encouraging thing for me.






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    • #215162
      Max A.

        Hello Luca,

        If you double the amount of light (lux/fc) you will obtain a stop of increment in your light measurement so you have to “compensate” with your “triangle” or nd.

        But I waiting for an answer of DP’s more expert than me.

        Have a nice weekend.



          Yes, if you go from 100 foot-candles to 200 foot-candles, you’d have twice as much light so would have to close down by 1-stop to maintain the same exposure. Or cut the ISO by half. Or close the shutter angle by half.



            I feel a bit like i had just discovered that you need fuel to make a car move, ah ah! But things are finally making sense for me!

            My problem is the ISO, actually. I don’t have  a very fast lens and i’d like to avoid to increase the ISO to keep the noise maneageable. So knowing the amount of light that  (more or less)  would gave me the same exposure is a big step for me. I realized that with a bit of creativity a small amount of additional light could help me solving the problem.

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