assist light is auto mode,
when ambient light is enough, the phone 'thinks' there's no need to on focus assist light. Save battery maa.. Of course, when it's dark or lowlight indoor, the led focus assist will turn on automatically.
Remember, the C901 oso same as the GreenHeart version on the software side. So, it's also power saving oriented phone.

Also, if you set the brightness to minimum (10%), there will be no blue led ring when you slide open the camera cover..
But if you set screen brightness to full, the blue led ring is there..

Yeap, when you set the screen brightness to minimum, the phone 'understands' that you wanna save battery as much as you can.. eventhough when you think again, there is no connection between blue led ring and LCD screen brightness.. 

Anyway, it's nice to know there are more and more C901 users around..
Click my 'fb siggy' below to view C901 flickr group pool..