The antireflection coatings are optimized to minimize reflections
from light entering the lens from the front and cross reflection in
the lens itself. Sensor back-reflection is an effect stemming from
less efficient reflection control from behind: light reflected
straight down onto the sensor, reflected back to the lens, then
bounced back to the sensor, caused by high specular reflectivity of
the sensor. It's a relatively rare phenomenon but it does occur with
some lenses.
I heard that one of the FA series macro lenses did this occasionally
and that it was corrected in the D-FA revision, but I don't recall
the source.
Stray light scatter off reflective surfaces in the mirror box, etc,
are the same as with a film camera.
Godfrey
On Sep 6, 2005, at 10:36 AM, J. C. O'Connell wrote:
Since modern multicoated lenses transmit more
than 99 percent of the light that hits them
(<1% reflection) I doubt that's ever visible.
A poorly designed mirror box or relflective
metals on the lens rear surfaces would be
more like culprits than the lens optics
in causing unwanted stray light reflections
I would think.
jco
