When using refractor telescopes, it's normal to see some purple-colored fringing
or halos around bright celestial objects. The V-Block filter effectively removes
distracting color halos from around bright objects viewed achromatic refractor
telescopes. Using a V-Block filter with a refractor telescope can greatly improve
sharpness, color, contrast, and resolution of especially bright celestial objects.
The Orion V-block filter is intended for both visual and astrophotographic use.