Sir Isaac Newton didn't use a specific, named telescope like the Hubble or the James Webb. He built his own reflecting telescope!

Newton was frustrated with the chromatic aberration (rainbow-like color fringing) of the refracting telescopes of his time. This led him to develop the first practical reflecting telescope in 1668. He used a concave mirror to focus light instead of a lens, eliminating the color distortion.

This invention was a major breakthrough in astronomy and paved the way for future advancements in telescope design.