The lines forming a cross in pictures of stars is a separate phenomenon. That is due to diffraction from the support structures of the secondary mirror. For a

The lines forming a cross in pictures of stars is a separate phenomenon. That is due to diffraction from the support structures of the secondary mirror. For a detailed answer to why the Einstein cross has 4 images, see: http://physics.stackexchange.com/questions/14056/how-does-gravitational-lensing-account-for-einsteins-cross http://physics.stackexchange.com/questions/14056/how-does-gr...