When placed into a conventional achromatic refractor, chromacor removes most of the false color (chromatic aberration), and corrects spherical aberration as well. This device was developed by Valery Deryuzhin of Aries (Ukraine).
Chromacor works better with several Chinese refractors made by Synta. These refractors vary a lot as far as optical quality is concerned and are known as "Celestron", "Bresser", "Konus", "Skywatcher", "Astroview".
The Chromacor corrects for chromatic aberration, spherical aberration and
spherochromatism. If a telescope has an excellent correction and its spherical
aberration is insignificant, then a Chromacor-N is a right choice. The Chromacor-N
corrects for chromatic aberration and spherochromatism only, without any effect
spherical aberration. If a telescope has significant amounts of spherical
aberration, then choose from four other types of Chromacors. These four Chromacor
types O1, O2, U1, U2, correct for different amounts of spherical aberrations
in the objective lens.
The following list summarizes the five Chromacor types.
Uncorrected image (left), corrected image (right) Click on images for full-sized view.
Comparison images (Synta 150 mm F/8 with matched chromacor). Daylight images.
Comparison images (Synta 150 mm F/8 with matched chromacor). Moon.
Comparison images (Synta 150 mm F/8 with matched chromacor). Vega. Chromacor is very sensitive to both alignment and centering. The focuser has to be properly centered and aligned using a cheshire eyepiece (see below).