How powerful are today's telescopes compared to some of the first used to look at the heavens?

In order to gather more light from faint objects, astronomers usually focus more on the aperture than on increasing the magnification. To answer your question, two of the earliest telescopes were made by Galileo and Newton. Galileo had a lens-based (refracting) telescope with a focal length of 980 cm (0.98m) and an aperture of 37 mm, and Newton had a reflecting telescope with a 50 mm mirror and a focal length of 15.8 cm. In summary, telescopes are used to magnify objects and make them appear brighter.

Numerous telescopes with apertures of 10 m and 30 m are being built today, and although these have fast focal ratios (short focal length relative to diameter), some telescopes from the 20th century have focal lengths greater than 30 m; the largest telescope in Canada is located at the David Dunlap Observatory and has a focal length of 34 m.

When these values are compared to the original scopes mentioned above, the DDO scope has an intrinsic magnification (focus length) that is 37.7 times greater than that of Galileo and 215 times greater than that of Newton. In terms of aperture, the Keck 10m telescope has 73,000 times more light gathering capacity than that of Galileo and 40,000 times greater than that of Newton!

Today's telescopes are significantly more powerful than the first ones used. Advances in technology allow for higher resolutions, larger apertures, and a broader range of observations.