Apochromats are refractors whose lenses are laid out in such a way as to combine at least three colours at a common focal point. This suppresses the chromatic aberration that is typical of refractor telescopes. Without this correction, bright objects like the Moon or the planets would have disruptive colour fringes.
TS Optics
Apochromatic refractor AP 80/480 ED Triplet Photoline OTA
RRP:
$ 1,180.00
Our price:
$ 770.00
Askar
Apochromatic refractor AP 71/490 Flat-Field 71F OTA
$ 1,120.00
William Optics
Apochromatic refractor AP 51/178 MiniCat WIFD OTA
$ 1,400.00
Omegon
Apochromatic refractor Pro APO AP 96/575 Triplet ED FCD-100
$ 1,290.00
William Optics
Apochromatic refractor AP 108/518 UltraCat WIFD
$ 4,920.00
Omegon
Apochromatic refractor Pro APO AP 85/510 Triplet ED FCD-100
$ 899.00
Omegon
Apochromatic refractor Pro APO AP 104/650 ED OTA + 2'' Field Flattener
RRP:
$ 2,059.00
Our price:
$ 1,999.00
William Optics
Apochromatic refractor AP 71/350 RedCat 71 WIFD
$ 1,750.00
Skywatcher
Apochromatic refractor AP 72/420 EvoStar 72 ED DS Pro OTA
$ 433.00
William Optics
Apochromatic refractor AP 51/250 RedCat WIFD
$ 1,180.00
Omegon
apochromatic refractor Pro APO DoubleED AP 40/180 Quadruplet OTA
$ 579.00
Omegon
Apochromatic refractor Pro APO AP 106/700 Triplet ED FCD-100
RRP:
$ 1,990.00
Our price:
$ 1,899.00
Omegon
Apochromatic Refractor Pro APO AP 71/490 Quadruplet OTA
$ 899.00
Askar
Apochromatic refractor AP 103/700 Triplet OTA
RRP:
$ 1,750.00
Our price:
$ 1,530.00
William Optics
Apochromatic refractor AP 51/250 SpaceCat WIFD OTA
$ 1,180.00
Omegon
Apochromatic refractor Pro APO AP 108/600 Quintuplet OTA
RRP:
$ 2,990.00
Our price:
$ 2,899.00
Askar
Apochromatic refractor AP 50/200 ACL200 OTA
$ 1,170.00
Omegon
Pro APO AP 72/400 Quintuplet OTA Apochromatic refractor
RRP:
$ 1,490.00
Our price:
$ 1,391.00
Omegon
Apochromatic refractor Pro APO AP 85/560 ED Triplet OTA
$ 1,690.00
Askar
Apochromatic refractor AP 55/264 SQA55 OTA
$ 1,180.00
William Optics
Apochromatic refractor AP 76/365 UltraCat 76 WIFD
$ 3,040.00
Askar
Apochromatic refractor AP 120/840 Triplet OTA
$ 2,340.00
Omegon
Apochromatic refractor Pro APO AP 110/660 ED Carbon OTA
$ 1,590.00
Skywatcher
Apochromatic refractor AP 80/600 Evostar 80 EDX
$ 670.00
ToupTek
Apochromatic refractor HOPE D60 60/280 f/4.66
RRP:
$ 1,229.00
Our price:
$ 999.00
Omegon
Apochromatic refractor Pro APO AP 66/400 ED OTA
$ 619.00
Askar
Apochromatic refractor AP 40/180 FMA180 OTA
RRP:
$ 750.00
Our price:
$ 510.00
William Optics
Apochromatic refractor AP 91/448 BlackCat 91 WIFD OTA
$ 3,980.00
Explore Scientific
Apochromatic refractor AP 80/480 ED FCD-100 Hexafoc OTA
$ 1,470.00
TS Optics
Apochromatic refractor AP 102/1122 SD OTA
$ 1,690.00
Skywatcher
Apochromatic refractor AP 70/490 Esprit 70 EDX
$ 1,080.00
OPT
Apochromatic refractor Radian AP 61/275 Raptor OTA
$ 2,570.00
Askar
Apochromatic refractor AP 60/408 60F Flatfield
$ 870.00
Omegon
Apochromatic refractor AP 96/575 Pro APO Triplet ED FCD-100 + Meade LX85 GoTo
RRP:
$ 3,190.00
Our price:
$ 3,099.00
Omegon
Apochromatic Refractor Pro APO AP 61/360 Triplet ED OTA
$ 599.00
ZWO
Apochromatic refractor AP 80/600 FF80
RRP:
$ 2,220.00
Our price:
$ 1,970.00
Refractors are telescopes where the objective consist of one or more glass lenses. The lens refracts light to a focal point. However, the exact location of the focal point depends on the wavelength (colour) of the light. This causes chromatic aberration which is noticeable as a coloured fringe around bright objects. In physics, this dependence of refraction on wavelength is called dispersion.
There is no really precise definition of the term apochromat. Most apochromats have an objective consisting of two lenses, in which a special glass is deployed. This so-called ED glass has particularly low dispersion (the abbreviation ED stands for extra-low dispersion). The ED apochromats provides a largely pure-colour image.
An objective consisting of three or four lenses will provide an even sharper image. These apochromats are called triplets or quadruplets. These can be as good as mirror optics in term of colour purity.