Observations of radio waves from astronomical objects suffer from poorer resolution than visible observations with the same size dish (or mirror) because Observations of radio waves from astronomical objects suffer from poorer resolution than visible observations with the same size dish (or mirror) because radio telescopes don't use solid mirrors. it is very difficult to detect radio waves. the signals are so weak in the radio region. radio telescopes are generally much smaller in diameter than optical telescopes. the wavelength of radio waves is much longer than the wavelengths of visible light.