Difference between two models, objects disappear from view, cameras added? I am quite confused and hope someone in this forum can help me out. When I add an object (Add > Mesh > Sphere) in Blender, it appears in the camera view at first, but then when I try to scale it, it disappears from view (I can still see it in Persp/Ortho View though). Also, a new camera appears all of a sudden? And why does the object seem to move when I change scaling - isn't it just supposed to get bigger/smaller? I do need the camera view, because the object should appear in front of a background image.

Also, I'm trying to figure out the difference between a blender model I received as model from my predecessor and my current version - I've attached both, something seems to be fundamentally different but I cannot figure it out. 

Ideally, the camera should look straight at the center of the sphere and the sphere should be in front of the background image.

I'm using this at work for research purposes and it would be really great if someone could help me! thank you!

my version (1st file), Model (2nd file)
In your 1st blend, you've checked "lock camera to view" in the "N" panel. This could have caused some strange things on the view and camera position.

You can't see your (flat) sphere because the sphere and camera are at the exact same Z position.

Move your camera up or your sphere down (on Z axis, use G, Z to constraint the movment on Z axis) and you'll be able to see it.