Focus: The Camera vs. The Eye

 I visited my local tidal wetlands this afternoon.  Again,  I lowered my point of view putting it among an aggregation of mussels. The tide was low. I aimed my camera directly at the sun for a backlit ( or contre jour ) effect which creates strong silhouettes and slight halos.  My biological eye is only able to focus on about 1% of my field of vision ( this explains why you cannot read a full page at a glance but, must scan the words).  My focus area is not only small but, it is also in the center of my vision.  Actually, we have overlapping fields of  vision with our two eyes so everything is really a little fuzzy unless we close one eye.  I must move my eye to expand my sense of focus by aggregating focus points. Look at the pink circle and you can see how much of your field of vision is in focus at one second.  My  camera focuses differently.  It also expands and contracts it’s aperture behind the lens ( like me with my iris). But, it can expand its depth of field to be much larger than mine. Even when the camera’s depth of field is small  it tends to make a strip of focus along a particular distance from the lens ( see the blue circled area). Notice that parts of the blue line are interrupted by objects not quite in focus. They are too close and outside the range of the focused depth of field just like the objects that are too far. Centuries ago when artists projected their subject matter on to their canvases ( Holbein, Jan Van Eyck, Caravaggio) by using concave mirrors they had to readjust or refocus their mirror to expand the area of focus. The image got blurry outside of the center just like our eyes.