Just some last thoughts and experiments concerning the “Sensor Size”:
1) “Auto” defines a squared sensor. The value is identical with the “Width” value that you can define with “Horizontal Sensor Fit”.
2) You can define custom sensor dimensions with the “Width” value set while “Horizontal Sensor Fit” is selected
and “Height” value set while “Vertical Sensor Fit” is selected.
3) Changing der “Render Size” resolution adapts the image to the sensor limits, changing the sensor resolution adapts the sensor to the render size limits.
4) I think the sensor settings only come into play when its about combining real life footage with computer animations. That’s confirmed by the Blender manual when it says that the “Sensor Size” setting “is useful to match the camera in Blender to a physical camera and lens combination, e.g. for motion tracking. ” For purely computer generated images, only the render resolution matters and the scene outcut is determined by moving or rotating the camera and zooming in or out.
5) No matter what “Sensor Size” is choosen (“Sensor Size” display switched in th active camera’s “Object Data Tab”), it’s always possible to render images that go beyond the limits of the camera sensor.
