It sounds like you're using "through camera" projection. If your source image is in spherical projection, then you should use the same "spherical projection" in the Image Map Shader. You will need to set the position of the shader to the same as the planet in order for it to work correctly.
If your image is *not* in spherical projection (for example a picture of Jupiter from a NASA probe), then you will not get proper planetary coverage, but you can still use it with through camera projection if you really want to. In this case you would simply make a copy of your main camera, keeping it static, and link your through camera texture projection to the camera copy rather than your original camera.
- Oshyan
