Hi,

There is a strange behavior with photons in an animation if the 
light_source is very dim in the first frame. 
(light_source{<1,1,1> color rgb 2*clock} for example)

Here is a scene to demonstrate it.
Change startval to change the initial brightness of the lightsource. If 
it is high enough that the photons are visible in the FIRST frame, the 
behavior is as expected.
If the brightness is just a little too dim for the photons to be visible, 
there are artefacts in the following frames.
And if th brightness in the first frame is very small (near zero)
there are no photons visible at all.

Ah, nearly forgot this: windows version, Beta 6

#version 3.5;

global_settings
{       
	assumed_gamma 2
	photons{count 30000}
}       

camera{location <-1,1.2,-3> look_at <0,.25,0>}

#declare startval=.1; 

/*
 *  <0.0001           -> no (visible) Photons
 *    0.001 ... 0.05  -> strange results in frames 2,3 etc
 *  >0.1              -> as expected
 */

#declare c=startval+clock*5; 

light_source
{
	<-5,2,0>
	color rgb c
}

plane{y,0 pigment{color rgb 1}} 

difference
{
	box{<0,0,-.5>,<1,1,.5>} sphere{<-.5,.5,0>,1}
	pigment{color rgb .1}finish{reflection .9}
	
	photons{target reflection on}
}

Lutz-Peter

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