EM Spectrum includes all of visible light, and longer and shorter wavelengths of light. All of our original observations were naked eye, visible light. The use of telescopes did not change the spectrum we could observe, just the range and detail.
We've really started looking at higher and lower energies since creating computer chips (CCDs), which we can front with detectors which absorb light at other specific frequencies. And more frequencies are available only because we can put the detectors in space, above our atmosphere, which stops high energy radiation.
We've gotten very clever in the last 15 years, and can work around the twinkling of the stars, essentially canceling out the movement of air in the atmosphere. But Hubble, and other orbiting telescopes, give great pictures without the post processing.
