With the Sunny 16/Basic Daylight Exposure rule, your subject has to be lit by sunlight in order for the exposure to be correct. However, as we all know, our subjects aren’t always fully lit by the sun. Your subject could be in the shadows, or it could be cloudy or overcast outside.
But one thing is still a constant, and that is the amount of light coming from the sun doesn’t change. That’s the beauty of the Sunny 16 rule. It’s just what could be blocking that sunlight that we have to take into account. And just as the Sunny 16 rule is pretty easy, so is it for adjusting for shadows or clouds.
For starters, the Sunny 16/Basic Daylight Exposure rule works quite simply by placing your aperture at f/16, and then simply matching your shutter speed to your ISO number. For example, f/16 with an ISO of 200, so your shutter speed is 1/200th of a second.
This works if your subject is lit by direct sun, allowing the shadows in the scene to fall, as they will. But if your subject is in shadows, or it’s overcast, we need to compensate.
If you subject is in the soft shadows, where sunlight is reflecting in or it is hazy outside, you open up, letting in two stops (+2) of more light. To do this, you can use your ISO, aperture or shutter speed.
So for example, using our previous exposure of f/16 at ISO of 200 with 1/200th of a second, letting in two stops of more light by taking it out of our shutter speed would be changing from 1/200th to 1/100th (one stop) and then 1/50th (two stops).
If you recall from our previous episode about shutter speeds, each full stop adjustment is either halving or doubling the number. We went from 1/200th to 1/100th (half) and then again to 1/50th, to achieve our two stops of compensation.
If your subject is in open shade, meaning that there is still light surrounding the open shade subject area, or it is cloudy, bright light, then you compensate by opening up (letting in more light) by 3 stops (+3).
If it is overcast or solid clouds outside, or your subject is in heavy shade, then you compensate by opening up (letting in more light) by 4 stops (+4).
Note that with the exception of the Sunny 16/Basic Daylight Exposure rule, all other exposures are approximate and could require slight adjustments based on the individual scene conditions. But the key here is that you are taking back control from the camera, and truly setting the exposure you see and want for your scene.