Yellow Sith eyes

[Imperator Galacticus]

I noticed while watching ROTS over the weekend that Vader's eyes didn't change to yellow until Obi-Wan had mutilated him and before when he was slaughtering the Separatist leadership.

Could this be because Vader hadn't crossed a certain threshhold point of dark side usage? Perhaps Vader wasn't channeling the dark side properly as other Sith can? Sith such as Darth Maul and Sidious had yellow eyes at all moments. Vader had them too at certain moments of intense hate and violence. Other Sith such as Count Dooku didn't.

As to why Dooku didn't, I would only dare to guess that he hadn't crossed the dark side threshhold completely. That would seem in line with his character acting in a mellow fashion. Maul and Sidious however appear to have given themselves completely over to the dark side's power, and in describing Anakin's characteristics, he reminds me in character similar to Darth Maul.

Seeing that Vader seemed to fade in and out of his dark side rages (he seemed to be completely Anakin when he saw Padme on the landing strip), and his "yellow eye" syndrome appears to fade when these intense rages subside, can it be summed up that the yellow color associated with most Sith Lords rises only when a dark sider channels a certain amount of power through themselves? What do you all think?

[Spetulhu]

IIRC Anakin's eyes glinted yellow when he marched out with the Clone Troopers to attack the Jedi temple. It's certainly a sign of Sith corruption that can either be suppressed or appear only when using the Force. It would be quite easy to discover Sith if their eyes were yellow all the time, wouldn't it?