Lumicon 72mm Minus Violet Filter
Lumicon 72mm Minus Violet Filter is used primarily to “bracket” the color-corrected band of refracting telescopes. This filter can also be used as a “visible” filter in RGBV (red-green-blue-visible) astrophotography with reflecting telescopes.
Most digital/CCD cameras have built-in infrared filters, however a minus violet filter may be used in addition depending on how far into the blue your primary lens is color-corrected. This filter blocks wavelengths shorter than about 420nm, reducing halos around objects for photography. Recommended for use with a telephoto lens to remove chromatic aberration.
Threads into standard 72mm telephoto lenses and may be used with other size lenses by using step-rings (view step rings, under Photographic Adapters).