I have a difficult time catching these birds with their ruby throat "turned on". It's not just a matter of seeing them from a certain angle. As I have mentioned in the past, these guys can minimize how much red is showing on their throats when they want to, particularly while they are perched. A good percentage of the time, their throats look almost black. I call it their "stealth mode". Then when a rival hummer shows up, they flash their ruby throat and go in chase.