[rollei_list] Re: Avedon self-portrait 1963
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: "New Rollei List" <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 16 Dec 2010 21:06:20 -0800
----- Original Message -----
From: "Don Williams" <dwilli10@xxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, December 16, 2010 5:55 PM
Subject: [rollei_list] Re: Avedon self-portrait 1963
At 12:37 PM 12/15/2010, Emmanuel Bigler wrote, in part:
In principle, a true self-portrait in a mirror should
deliver a
reversed image with the release button of the 'flex in the
left-hand
of the photographer ! And a direct, non-reversed image, if
the camera
was relased with a long (pneumatic ?) cable release !!
A little amusement- When you look at your image in the
mirror and move your right hand the person in the image
"appears" to move his left hand, thus "reversing" the
image. Assuming this is true, why isn't the image
inverted so that the feet are above the head.
One more, forgive the grammar- I can tell you what time it
is but can you tell me what time is?
DAW
Its because the mirror does not really reverse anything
except the direction of the light waves along the axis of
observation. When we move so that we occupy the same
position as the mirror, and are facing the same way, we
actually see everything in the same position as the mirror
does but _we_ have rotated 180 degrees in a single
direction, usually left to right, so our perception of the
image changes. Actually, when facing a mirror you are seeing
what goes on in front of the mirror from the back from the
viewpoint of either the mirror or someone standing where the
mirror is. Since the axis of rotation of the observer is in
only one direction the other axis appears to be the same.
Note the distance is also "reversed". If you toss a ball at
the mirror it will appear to be approaching you. Again, its
the position of the observer that has changed.
If you arrange two mirrors in a 45 degree V the
reflected image will appear to be correct left to right.
This is an interesting exercise. It can be carried out with
ordinary mirrors but works best with good quality
first-surface ones. It will quite disorient some people plus
people are fascinated to see themselves as others do. Such
mirrors are called corner reflectors and three-dimensional
versions are used for reflecting light back to its source
regardless of the orientation of the mirror. The reflectors
used for surveying are made this way as are corner reflector
antennas for use on life boats so that the make a strong
radar return. The small reflectors in hiway signs are also
corner reflectors intended to return the light from your
headlights to you regardless of the position or motion of
the car.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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