I want the camera to follow an object ( the objects position). For example think of some red blood cells floating down a vain or some kind of tube, i create an emitter and want the camera to follow one of the objects from the emitter though out the tube.
In that case it depends a bit on how the object is animated. For example, if it's just a regular object KF'd by hand you could simply make the camera a child of the object, or use the Timeline's motion path to spline function, and then align the camera to the spline. Or you could use a PSR constraint (characher>constraint tag).
Particles or mograph objects are a bit more complicated as you have to ascertain the index of the particle you want to use and then obtain the position data. What I would do is clone onto the particles and then use the mograph data node to get that info. You could then have a null follow the particle and have the camera follow the null (or offset it and make it a child of the null).