Camera tracking: Moving the camera too much I am working on a scene which is a corridor, and I want it to seem like someone is "holding" the blender camera while running down the corridor. I asked how I would accomplish this and someone said to hold a camera in real life and run down a hallway with contrasting objects that can be tracked. So I went ahead and did this, however, the way I want it to show up and the way I filmed it I moved the camera around and looked at the walls and moved in different directions to make it look like the person running down the corridor was looking around, which means that the markers come in and out of view and no marker stays in the view the whole time. How can I make it so that when Im looking straight at a marker it is tracked and then when I move the camera away to look at the wall then back straight ahead the marker is then tracked again? 

Sorry about the long question thanks in advance for the help.
You should use weighted tracking; To do this, go to the Motion Tracking perspective, select a marker, and open the Properties Panel(N) and go to the subsection "Track"; There is a field labeled Weight, which controls the importance of that marker; 



Like most fields in Blender, this can be animated. What you need to do is make this field change, such that when it's almost out of view, the weight is 0, then, when it gets back in inside the Camera's frustum (Camera's View) make it go up again, 1 being the maximum; Keep in mind you shouldn't just make it 0 all of the sudden.