In this post, I will cover another aspect of luminosity, however, this time I will provide some real life examples.
Previously I wrote about the influence that time and latitude have on the rule "sunny 16". In this post, I will have to make use of the influence that local time.
For taking the following images, I went out later than 6pm local (MEST), therefore, I opened the aperture by 1 stop to f/11.
The 3 following photos were taken from the very same spot, with an essentially cloudless sky, and the camera set to s/250 and ISO250. Please observe the shadows to determine the direction of light.
|0˚, f/11, s/250, ISO250, front lit|
|90˚, f/8, s/250, ISO250, side lit|
|180˚, f/5.6, s/250, ISO250, back lit|
In the last photo, you may notice the lens flair, which was created by shooting into the glaring sun.
You will notice that the mid-ground (the trees) is perfectly exposed in all three photos. Of course the highlights will be blown out when shooting into the light... no surprise here.
Comparing the 0˚ and the 90˚ photos, you will notice the balance of the tree's highlights and shadows are the same, while contrast and highlights are more pronounced at the 90˚ shot. At 180˚, the contrast is somewhat "back to normal", when accepting the blown out highlights.
There is also a noticeable difference in the exposure of the sky. At 0˚, the sky is exposed the darkest. Since the brightness of the sky is independent from the scene, when opening up at 90˚, the sky portion of the image receives more light and is therefore brighter in the photograph. (At this angle, a blue sky can be recovered by use of a polarizing filter, which I will discuss in another post sometime later.)
Concluding: use the sunny 16 rule when shooting front-lit scenes. Open up 1 stop for side-lit scenes, and 2 stops for back-lit scenes.
I hope that this brings you a bit closer to understanding exposure and lighting under given circumstances.
In future parts of this series I will explain how to determine the illumination under circumstances other than an open blue sky.