[Leica] BOKEH of the human eye

["Clompus, Dr. Richard [INN]" <RCLOMPUS@INNUS.JNJ.com>]

Dear Fellow LUGnuts,

I read with interest the post by Dan Post about how some photos are more
pleasing to the eye and how perhaps the human visual system corrects certain
images.  As an optometrist, I have spent the last 20 years helping my
patients to see better.  During this time, I have acquired a greater respect
for the human visual system.  The retina is essentially a piece of brain
tissue that is extremely well suited to provide not only clear vision
centrally but excellent peripheral vision as well.  About 30% of your brain
mass is dedicated to visual processing.  It is located at the back of your
head called the occipital cortex.  If you get hit hard enough on the back of
your head in a car accident, you can become blind even though the eyes are
perfectly normal.  

Many of the optical properties that gets us so excited such as depth of
field, field of view, focussing and coordinated eye movements are "simply"
automatic for us.  Spectacle lenses introduce chromatic aberration,
distortion and spherical aberration but miraculously your visual system
adapts to all of these.  After wearing a new pair of glasses or contact
lenses for a few weeks, your visual system in the majority of cases adapts
automatically to produce clear and comfortable vision.  You don't have to
think about it, study it or work at it.  It just happens.  

Camera lenses are unique in that they have optical qualities that do not
usually change over time. You can pick and choose your favorite distortion
and aberrations that please you the most.  If it's built well, you can use
that lens for a lifetime.  Its aberrations will always remain the same.
It's not biological.  We all have favorite lenses that just make better
pictures.  What I have learned as I have aged as an amateur  photographer is
that I prefer some Leica lenses a lot and in some cases have not upgraded to
the latest rendition - even though the news lens may have better optics.
I'm learning that newer isn't necessarily better.  Heck I listen to music
with a British solid state amplifier (NAIM) but I also like the music made
through a new tube amplifier (Ravin) made in the U.S.   I still prefer film
to digital but if Leica made a digital camera that would accept M or R
lenses that I could afford without selling my car, I'd try that too.

Its Friday.  Have a great weekend.  I've got a glass of single malt scotch
at home with my name on it ready to be imbibed.  

Richard
Richard Clompus, OD
Roanoke, VA