Definition of "View Angle of Human Eye"?

I've been told (since high school I think) that "view angle" in a 2-dimensional plane is approximately (distance to the object/object's length).

The assumption is that I'm viewing an object [itex]AB[/itex] of length [itex]L[/itex], basically a segment in a 2-dimensional plane; [itex]AB[/itex] stands at a distance [itex]d_v[/itex] away from my eyes, like shown in the figure below. To make everything simple, [itex]AB[/itex] is perpendicular to the horizon and my eye is looking straight along the horizon.

Is the view angle for my eyes [itex]\frac{d_v}{L}[/itex] ?

The problems which are confusing me are:

1. If I put a convex lens between [itex]AB[/itex] and my eyes, how would it change my eyes' view angle of the object?

2. Based on problem 1, if my eyes is replaced by a silver-halide grained film, like an old camera, what is the definition of view angle now? Would it be related to the size of the film and size of the silver-halide grains (To my understanding this affects how clear a photo is captured)?

3. Back to discussion of human eyes (no external lens or film),is view angle affected by the focal length of my lens(in the eyes)?

Any help will be appreciated :)

Attached Images

Screen Shot 2013-07-26 at 12.00.44 AM.png (20.0 KB)