Even thou this is more of a standard beginner issue I decided to post about this, there is an increasing amount of beginners who take interest in the awesome Cinema 4D so this issue is always current. So you got your Cinema 4D open and started to model something awesome (of course...) and you zoomed in on the pesky little vertex that gives you trouble only to see that vertex and part of your model gets cut-off when you get close to it?! No worries that is just something called Viewport Clipping
In 3D computer graphics, there is thing called the "View Frustum" it is the region of space in the modeled world that may appear on the screen; it is the field of view of the camera in question.
Frustum "is a portion of a cone or a pyramid which remains after its upper part has been cut off by a plane parallel to its base, or which is intercepted between two such planes."
The "View Frustum" is the adaptation of (idealized) cone of vision that a camera or eye would have to the rectangular viewports typically used in computer graphics. The planes that cut the frustum perpendicular to the viewing direction are called the "near plane" (A) and the "far plane" (B). Objects closer to the camera than the "near plane" (A) or beyond the "far plane" (B) are not drawn. Sometimes, the "far plane" (B) is placed infinitely far away from the camera so all objects within the frustum are drawn regardless of their distance from the camera.
Viewing-frustum culling is the process of removing objects that lie completely outside the viewing frustum from the rendering process. Rendering these objects would be a waste of time since they are not directly visible.
So in my case, as I demonstrate here is that my lighter is too close to the cameras "near plane" (A) so part of my model falls out of the "View Frustum" and that's why there seems to be missing a piece.
Well, how do we solve this issue? I really really would like to see my model up close and whole, probably you feel the same way so let's get on with it.