Depending on system, it is...
Xbox 360 - Y = L in this game for eagle vision you should push left joystick ( to down ) push left joystick into down
PS3 - Triangle
PC - E
In AC1, you need max synch to use it.
Yes, there is Eagle Vision.
He dosen't get a power he learns the ability of eagle vision.
Use eagle vision to spot your target then chase her. (Not to kill, follow)
use eagle vision to locate maria then follow her
you alternate on the three patches of hay or use your eagle vision to see them(they will be blue).
if your meaning in 2012 in Monterigionni then put on Eagle Vision and you'll see then throughout the town.
you find the truths left by subject 16 in the past written on buildings that can only be seen in eagle vision
Once the cutscene has ended, go to your room and use eagle vision. Then you will see the credits.
If your talking about the ones when you use eagle vision...then its blood that subject 16 left as clues for Desmond to find in the animus.
Do you mean any of these by chance? (1) How did you unlock eagle vision? (2) what button do you press for eagle vision? (3) how is eagle vision useful? (1) i don't really know the answer for this, but i think you just so happen to use it the first time you need to. (2) Press the left rotating button or (L) as others call it (3) Eagle vision is useful for seeking out allies, adversaries, or assassination targets.
There are a few extra things, such as collectables and also eagle vision points, and if you talk to some people, you can do some races and also some side quests, if you're bored of the main storyline.
Al Tahir, meaning "The Flying Eagle".