Optimal brightness setting?

What is the best screen brightness setting, especially for viewing videos?

I'm testing between 80 and 100. But I can't really tell much difference, so I'm sticking with 80 for now.

The reason I ask is because my brother has an Iriver Clix with has a much clearer and natural coloured screen. I'm wondering if my brightness setting will improve the M6s.

What does everyone else think?

For videos I use 90, otherwise it is set at 40.

Get a gamma chart image - the grayscale ones from black to white in steps. Set it as your background and then adjust the brightness down as far as it will go and slowly move it up until there is a noticeable difference between the darkest and second darkest shades.
Try http://www.mediacollege.com/images/i...reyscale01.gif for a chart

I use 90% setting for both menus etc as movie and pics
This gives a nice bright screen...and a good contrast with the black of the player.
for text I turn down the background blend to 12 or so to make the letters stand out more...

Ok thanks for the suggestions