Depth of Field. Conversely, for a given film position, there is a range of distance at which all objects have acceptable images on the film . This distance is called the depth of field . Within the depth of field, all objects are reasonably clear on the film.
f = 50 mm, d = 12.5 mm
Then f/d = 4,
which is written as f/4.
In a bright sunny day…
f/11 and 1/60 sec
f/8 and 1/120 sec
Gives the same exposure
If an object is moving, you want to have shorter exposure time.Choosing Exposure
See 25cm away
We use many different cues (a feature indicating the nature of something perceived)
However, they are intrinsically ambiguous, can be interpreted in
many ways. We interpret in the most likely possibility.