Influence of Focusing on Exposure

Since the sky area has been focus, it is rendered as Grey or the middle tone The focusing point is lower towards the darker area, which is why there is relatively more detail in this portion.


focus and exposure low 1 focus and exposure low 2 focus and exposure low 3

24 mm f/4 1/125 at f/16 Evaluative metering

Here the focus is on the houses in the background rather than the foreground. The exposure of the focused area is fine and the bricked foreground is dark. Our eye sees the brightest area in the photograph first of all followed by the darker ones. Ideally your main subject should be correctly exposed rather than the supporting elements.


105 mm f/4 1/200 at f/9 Evaluative metering

On the other hand the wall has been focused and hence not rendered dark but in a middle tone. The background is over exposed. Its always better to include dark tones in a photograph compared to washed out ones.

Left- The focusing point is almost on the outside ( the camera must have been shifted down a bit after focusing) with the inside a bit dark. on the right, when the focus has been shifted inside the exposure is correct for inside compared to outside which is a bit washed out. 

The difference in the exposure is quite visible when photographing the yellow board along with the white car. when focused at the board the white car is quite washed out. In the other case when focused at the car, being white the exposure is quite deep towards the darker side. Details are quite visible and well exposed in the car and the board is too dark.