Galileo Galilei built his first refracting telescope in the month of May 1609 while visiting Venice. He constructed this instrument using available glass to magnify distant objects about thirty times.
Chester More Hall created the first twin color corrected lens in 1730 as an English barrister. This design combined crown glass with flint glass to bring red and blue wavelengths into focus simultaneously.
The largest practical lens size remains around forty inches due to physical constraints like sagging under gravity. Glass defects known as striae or small air bubbles trapped within the material further degrade performance for larger designs exceeding one meter.
Christiaan Huygens found Titan, Saturn's largest moon, on the 25th of March 1655 with a Dutch telescope. Asaph Hall identified Deimos on the 12th of August 1877 at about seven forty-eight UTC from Washington D.C.
Chromatic aberration creates purple halos around bright objects in shorter focal ratio achromats while eight-inch models show considerable color fringing. Most of these problems are avoided or diminished in reflecting telescopes which allow far larger apertures without such distortion.