Lumicon Minus Violet Filter - 72mm
The Lumicon Minus Violet Filter greatly improves photographs taken through lenses of any type. This filter is made from optically flat specially-made colored glass, and has anti-reflection coatings on both surfaces. It is especially recommended for all telephoto lenses, and will help you obtain pinpoint star images. The Minus Violet filter passes the maximum amount of visible light, including the full blue, green, yellow, and red portions of the spectrum. It absorbs violet and ultraviolet light below 420nm and thus eliminates blue halos around bright stars in color photography. In B&W photography it eliminates bloated and swollen star images caused by violet and ultraviolet light which telephoto lenses cannot focus, due to chromatic aberration. The Minus Violet filter slightly reduces light pollution.
Recommended Films - All films can be used with the Minus Violet Filter; hypersensitized 2415 is the recommended B&W film
Filter Factor - Increase exposure by only about 10% for the Minus Violet Filter.
For Viewing - The Minus Violet Filter can eliminate or greatly reduce the blue halo sometimes seen around stars in refracting telescopes. It is ideal for observing the moon and planets.