Maybe I'm doing something different to you, but I see no effect on the object brightness when scaling the object using the following code:
sync on
sync rate 0
scale# = 1.0
load object "Con_5.X", 1
do
if upkey() then inc scale#
if downkey() then if scale# > 1.0 then dec scale#
set cursor 0, 0
print "Scale = "; scale#
set camera range scale#, scale# * 20
scale object 1, scale# * 100.0, scale# * 100.0, scale# * 100.0
position camera 0.0, 0.0, scale#*-2.0
point camera 0.0, 0.0, 0.0
sync
loop
So what are you doing differently to me?