Please restate. Your sentance We have an observer, who is also in in this field observer a deflection? How? is meaningless to me.Ok, so suppose we have a photon that is emitted and absorped between A and B in this field. We have an observer, who is also in in this field observer a deflection? How?
Huh? What do you mean by "observer is not in the field"? By definition the observer is in the field. That's precisely how one interprets the physical meaning of spacetime coordinates. Let mf give you an example: consider an infinitely large plane of unifrom mass density. This will generate a uniform graviational field. The field is uniform for observers who are at rest with respect to the source, e.g. standing on the plane.Only observers outside your field would observer a "deflection", but this "deflection" is not due to to the field but due to the fact that the observer is not in the field.
If you'd like me to respond your questions then please respond to mine so that I may better answer yours. Thanks.
By the way, have you ever read any of Einstein's writings such as his book on SR and GR? Think of what an observer in an accelerating elevator would see if a beam of light is initially directed parallel to the floor of the elevator. The elevator would continue to accelerate after the light is emitted and thus the path of the light as observed from the elevators accelerating frame of reference is a curved path. This is identical to what one would view from an observer at rest in a uniform gravitational field.