What effect does the size of a black hole have on the size or density of the photon sphere and it's proximity to the horizon?
For example: A person is in space looking at 2 black holes, one of them big and the other small. Could the bigger one appear smaller because of the way space bends around it?
If yes, can a large enough black hole be completely hidden behind the gravitational lensing? Could a dense photon sphere around a black hole look like a spherical distortion to distort the horizon or hide the black hole completely?