To demonstrate how focus affects the perception of depth in a photograph I took a series of three images with the same composition and three different focal points. Shot 1 was focused far right of the frame, shot 2 in the middle and shot 3 far left. This was to accentuate the different focused/out-of-focus points. The photographs were taken with the largest aperture my camera would allow.
My thoughts are as follow;
Initially I assumed shot 1 would be my favourite. It somewhat leads the eye in to the rest of the frame. However, only the middle of the word is in focus (due to the small plane of focus being used) and as such makes for uncomfortable reading. So actually, number 2 is my favourite as the whole of the word ‘FRIEND’ is in focus which makes it far more comfortable to look at (in my opinion) and still leads the viewer in to the rest of the frame. Shot number three gives the illusion of being completely out of focus until you reach the far left side by which time the details make no sense to the viewer.
It is also worth noting that although these shots are all identically composed, they give the illusion of ‘shifting’ in the frame when viewed one after the other. This is caused by focusing through different parts of the lens for each image.