ED Air-Spaced Triplet APO Refracting Telescopes
Apochromatic (APO) lenses are designed to bring three wavelengths of light (red, green, and blue) into focus in the same plane. In contrast, achromatic lenses are corrected to bring two wavelengths into focus in the same plane.
The classic achromatic doublet made from optical crown and flint glasses bring two colors of light to a common focus. This diagram shows the image forming lens in the front and the correcting lens in the back.
Apochromat optics were first developed by Peter Dolland in 1763. His air-spaced triplet design ushered forth many optical improvements but lacked the use of ED glass that we see in most apochromatic optical designs today. ED glass enhances apochromatic lens design by producing extra-low dispersion of the wavelengths of light passing through it thereby giving an even better apochromatic performance. For more specifications and information on the different types of glass used in Explore Scientific apochromatic triplets, please click here.
Explore Scientific true apochromatic telescopes utilize three air-spaced elements with the ED element in the middle to bring the light of three different frequencies to a common focus, thus mitigating the effects of chromatic aberration.
Explore Scientific ED102 Essential Series Air-Spaced Triplet APO Refractor Telescope - ES-ED10207-01Explore Scientific
Description Temporarily Out of Stock, But More are On The Way! The Explore Scientific ED102 Essential Series is Available for Back-Order Purchas...View full details$ 1,199.99
Description Temporarily Out of Stock, But More are On The Way! Estimated Restock Date is the End of July . The Explore Scientific ED127 Essential ...View full details$ 1,899.99
Original Price $ 1,899.99Current Price $ 1,399.95
Certified Pre-Owned Explore Scientific ED127 Essential Series Air-Spaced Triplet Refractor Telescope - ES-ED127075–03Explore Scientific
Description The Original Classic Explore Scientific ED127 Air-Spaced Triplet, Retooled for the Astrophotographer: New precision front cell with ...View full detailsOriginal Price $ 1,899.99Current Price $ 1,399.95
$ 1,899.99$ 1,899.99Sold out
This item is currently out of stock and on backorder. Estimated restock is July 2021. Partial payment pre-orders require 5% to reserve the item. Wh...View full details$ 2,399.99Sold out
ED140 FPL53 140mm f/6.5 Air-Spaced Triplet ED APO Refractor Telescope in Carbon Fiber with 3" HEX FocuserExplore Scientific$ 5,999.99Sold out
ED115 FPL53 115mm f/5.5 Air-Spaced Triplet ED APO Refractor Telescope in Carbon Fiber with 3" HEX FocuserExplore Scientific$ 3,499.99Sold out
Explore Scientific FCD100 Series 127mm f/7.5 Carbon Fiber Triplet ED APO Refractor Telescope with 2.5" HEX FocuserExplore Scientific
This item is currently out of stock and on backorder. Estimated restock is August 2021. Partial payment pre-orders require 5% to reserve the item. ...View full details$ 2,999.99Sold out