Bill, The flash is effectively "more powerful" in a smaller room if the angle of the beam is much larger then the angle of the view of the object. Let me give you an example where it is not true. Imagine you are using a flash with an angle of the beam that is similar to the angle of view of your lens (and the design where all the light is thrown forward) and the object you are photographing takes most of the frame. In this case, presence or absence of the wall would not matter. (This situation is somewhat equivalent to macro-photography with a flash).
While I do not know how exactly GN is calibrated in reality, I would expect it to be based on the direct light exposure, without taking into account the light bounced of the walls/ceiling. In this case, the "average reflectance" is related to the object(s) being photographed, and not to the surrounding objects (outside of the frame). Igor Thu Feb 28 18:40:38 EST 2008 William Robb > I have heard about the GN being based on an "average reflectance" > scene (the average room, if > such a thing exists). Some say it is myth, others say it is true. A > flash is definitely "more > powerful" in a smaller room than a very large one or outdoors though > because of all the light > bouncing around. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
