Telescopes classed as apochromats with a doublet lens have a two-lens objective design. The classification no longer makes a distinction between semi-apos and two-lens apochromats.
The second element is usually made of ED glass (ED stands for extra-low dispersion). However, minor chromatic aberrations are still visible, since only a triplet apochromat with a three-lens construction can completely correct them.
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Lunt Solar Systems
Solar telescope ST 70/420 LS60MT Ha B1200 Allround OTA
$ 2,180.00
ready for shipping in 6-10
weeks
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Lunt Solar Systems
Solar telescope ST 80/560 LS80MT Ha B1200 R&P Allround OTA
$ 4,130.00
ready for shipping in 6-10
weeks
