P3D Unique flash use w/RBT S1! - Part II

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Thanks to Bill Costa, I now understand how the flash really works 
with the S1:

The camera essentially takes two exposures:  One for ambient light
and one for flash.  If the ambient light is very low then the camera
will default to the maximum aperture and slowest allowable shutter
speed (1/30 is the default but it is user-defined) AND THEN quickly
close the aperture and fire to flash to give correct exposure 
according to the (known to the camera) distance to the closest object.

This explains why my flash pictures have this very nice ambient
illumination, instead of the harsh flash light when the subject is
sufficiently close to trigger small f-stops.

For example, I took two pictures with my son and wife at about 3 feet.
The display in the camera indicated f16 for the proper flash exposure.
Picture #1 was taken with the camera in P.
Picture #2 was taken with the camera at f16 and 1/30.

According to my earlier (false) understanding of the flash operation
there should be no difference between #1 and #2 because in #1 the
camera will use f16 at 1/30.  HOWEVER, the camera does two exposures,
one at f2.0 at 1/30 and one at f16 and flash.  The result of these
superimposed exposures is that the shadows are filled with ambient
light resulting in a very pleasing (not harsh) image that I like a lot!

THAT'S SOMETHING THAT EVEN THE REALIST CANNOT DO!!! :-) 

Needless to say, not many people understand this flash operation and
the manual is of no help.  I don't know how Bill got his facts straight
but he must be a very bright guy!  He also checked the camera with the
back open and CONFIRMED that the aperture changes when the flash 
fires at the end of the exposure. 

Thanks Bill!  (and thanks RBT S1 for making low-light single-flash 
exposures so easy to take and such a pleasure to view!)

George Themelis


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