Why do I have a strange kink at the edges of the tiles? I'm using Blender Render, a 90° FOV Camera. My Tiles are 512x512.

But when rendering, there is something strange happening at the edges of the tiles. Does anybody know something about it?
Ah, i found the problem myself!

I set the camera to Panoramic instead of Perspective

Now I changed it to Perspektive and the edges are gone.