Lenzfx
Scott,
No hard feelings. I actually love a good heated argument, umm, I mean debate.
Just ask my brother. It's a wonder we BOTH survived childhood.
<<So maybe I am way off base, but if I am then could someone explain to me how
you are able to look at one of those stereogram posters and change your focus
from the image to the reflection on the surface?>>
The poster and the poster's glass case (I'm assuming this is the reflection
you're talking about) are two completely different surfaces.
<<Maybe I am reading what you are saying wrong, but your argument seems to say
that the reflection would always be in focus when the reflector is in focus.>>
Only if your reflecting surface is a perfect mirror. And a perfect mirror is
nearly impossible to find naturally. Most surfaces will at least slightly blur
a reflection, that's why 3DS gives you the reflection blur slider.
<<Another example would be in a movie when there is a shot of a rear view
mirror and the reflection is in focus while the mirror is not>>
A focal effect is actually due to the differing angles that light enters a
camera or your eye, and the lens element composition and placement in the
camera (in the case of a camera) or the shape of your cornea and eyeball (in
the case of your eye). Light coming from different depth planes of a scene
generally reach your eye at different angles and thereby gives the classic
depth-of-field focus effect. However, it is easier for us to think of focal
effects based on distance rather than a bunch of angles and lens refractions.
Early cameras were pretty simplistic though and often relied on the exact
center of an image to be the focal point and then blurred the edges of the
image. This is probably what you're seeing in the rearview mirror example.
Aaron