Reducing this flaw requires turning to premium apochromatic
refractors, which employ exotic and expensive glass.
lenses correct chromatic aberration for three wavelengths of light, often used in super-telephoto lenses.
This stunning view was captured with forty 5-minute exposures with a DSLR mounted on an 80-mm apochromatic
For instance, one might put an apochromatic
refractor onto a heavyweight equatorial mount for astrophotography but use the same scope on a lightweight altazimuth mount for airplane travel.
DETAILS: Sky-Watcher Esprit ED80 apochromatic
refractor and Moravian Instruments G2-8300 CCD camera with Astronomik LRGB filters.
The expense of completing my master's degree forced me to sell most of them, but I think I've come up with the perfect urban telescope: a 3-inch apochromatic
(highly color-corrected) refractor on an altazimuth mount (one that simply moves up and down and side to side) with slow-motion controls and a simple sighting device.
DETAILS: Takahashi TOA-130 apochromatic
refractor and QSI 690 CCD camera used with LRGB filters.
These are referred to as apochromatic
lenses and are essentially free of chromatic aberration, but you pay a premium for this level of performance.
The f/8 configuration is similar, with an apochromatic
Barlow in front of the secondary and additional lenses built into the drawtube, which results in a low 25% central obstruction.
" models in 4-inch and larger sizes use lenses made from special glasses to eliminate false-color fringing around bright objects.