Excuse me, bb, but you are not reading my posts properly. I did not keep the same shading rate in the smaller render, I reduced it by a factor of 4, the same as the increase in size for the other render.

And there was a need to do the test. You know lots of things that I can only find out by experiment. You are the one who always says "show me"!

:O)

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)