Big refractor

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Several observatories refer to their largest lens telescope as the large refractor . These instruments, which were around 10–20 meters long and weigh tonnes, were developed before the turn of the century and were popularly known as giant telescopes . For weight reasons, the development ended in 1897 with the 102 cm lens of the Yerkes Observatory , the lens doublet has a total mass of 230 kg and already sags noticeably under the force of weight . Then the era of the large reflector telescopes began .

The big refractors are - ranked according to their year of origin: