When observing multi-star systems with a naked eye, one often gets the impression that he is looking at a single star. The binary - or multiple - nature of stars in such systems may become visible if one were to use good binoculars or a telescope.
This model illustrates the changes in appearance of a single multiple system as it is observed at different degrees of magnification. A naked eye may only discern one star (ε Lyra) situated close to Vega. Using binoculars with six-time magnification will reveal two stars (ε1 and ε2). Finally, when observed through a telescope that magnifies by 170 times (in which case Vega does not have enough room in the field of vision), each of the two stars of ε Lyra will break into two components.