Chevalier made an achromatic meniscus lens, from where the Lomography Art Daguerreotype Achromat
draws its inspirations from.
This premium refractor for lunar and planetary observing sports a 4-inch (100-mm) achromat
with a focal length of 1,000 mm (f/10).
It's also possible to use extra low dispersion glass in one of the elements to produce an ED achromat
Al Nagler calculates that the TV-60's color correction is equivalent to that of a traditional f/25 crown-flint achromat
8-inch (70-mm), 700-mm-focal-length (f/10) achromat
with an altazimuth mount, integral dual-axis drives, and an adjustable aluminum tripod.
9 Lens type Achromat
Apochromat Focuser size See note (5) 1 1/4 inches Carrying case Included Optional Tripod mounting block Included Optional (8) Minimum tube length 10 1/4 inches 15 3/4 inches Weight 1 lb (0.
The residual spurious color of an ordinary achromat
cannot be totally eliminated, but it can be reduced to almost imperceptible levels if the focal length of the lens is sufficiently long.
Better telescopes come with Kellner (K), Modified Achromat
(MA), or, better yet, Plossl eyepieces.
By the way, achromat
means "without color," while apochromat means "without color--but, we're serious this time.
It is a short-focus achromat
, which at first glance appears similar to other low-cost, short-tube refractors.
In spite of several problems inherent in its design (especially chromatic aberration), a wellmade achromat
is capable of producing superb views that are rich in detail with little false color.
The Vixen 114-ED's color performance was very good, and it is far better than any f/5 to f/8 achromat
, but still not the equal of apos such as Vixen's own VX102-FL f/9 fluorite refractor.