The object of this exercise is to understand how depth of field ‘reacts’ in conjunction with the distance to the object being photograph.
These two shots are almost identical in framing. All I have done is alter the point on which I am focussing. The glass in the window frame has accentuated the effect of what happens. I have also used a relatively shallow DoF when shooting to accentuate the point.
Using a Canon 5dII with a EF24-105mm lens I have shot the first one at f4.5 @ 1/250th/sec with a focal length of 105mm and ISO 1600. The settings of the second shot vary only in the shutter speed (1/125th, camera set on Aperture priority), and the subject distance (11.9 & .8m).
What can be seen and deduced from the two images is that the closer the subject matter, the shorter the DoF, and conversely, the further the subject matter from the lens, the greater the DoF. This is clearly demonstrated below. The first image, I focused on the gate, and the amount that is in focus I would estimate to be about three feet. in front of the gate and about 9-10 ft beyond the gate. In contrast to this; In image two the foremost of the window frame is in focus, but by the time you get to the outer window frame it is completely out of focus. A total DoF of no more than six inches.
Generally speaking a close sharpness and distant ‘blur’ is more pleasing on the eye, but I think in this instance, comparing like for like, it is the other way round. The blurred window frame is acting as a guide through the window from inside the house to the gate at the bottom of the garden. With the diagonal ‘lead lines’ in the garden the ensemble as a whole work very well to create a good ‘journey’. The softness of the frame does not impede the journey in the way a focussed frame would (by halting the journey to study the detail in the frame). Image two is a very flat image, and imparts a feeling of being imprisoned.
I see! 