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.
Lunt Solar Systems
Solar telescope ST 70/420 LS60MT Ha B600 Allround OTA
$ 3,870.00
ready for shipping in 1-2
weeks
Lunt Solar Systems
Solar telescope ST 70/420 LS60MT Ha B1200 Allround OTA
$ 4,520.00
ready for shipping in 1-2
weeks
Lunt Solar Systems
Solar telescope ST 80/560 LS80MT Ha B1800 BT R&P Allround OTA
$ 9,000.00
ready for shipping in 1-2
weeks
Lunt Solar Systems
Solar telescope ST 80/560 LS80MT Ha B1200 R&P Allround OTA
$ 8,200.00
ready for shipping in 1-2
weeks