What optical drawback is specifically introduced by the secondary mirror in a reflector design?

Answer

Diffraction patterns around bright stars.

The secondary mirror in a reflector must be held in the light path by spider vanes, which cause a faint diffraction pattern, often seen as a cross or starburst pattern around bright stars.

What optical drawback is specifically introduced by the secondary mirror in a reflector design?
astronomydisadvantagesadvantagesopticstelescopes