SKU: GCE200

Description

The Galaxy Contrast Enhancement™ filter aids in the visual observation of galaxies and milky way dust clouds and dark lanes. The GCE filter takes a different approach to enhancing galaxy observation by allowing high transmission through nearly the entire visible spectrum while rejecting only the harmful light pollution wavelengths. Because of those attributes it also is a very good general purpose LPR filter, unlike traditional wideband filters which exclude most of the red portion of the visible spectrum.

Spectral Curve

Specifications

The GCE filter design stresses maximum optical throughput utilizing state-of-the-art optical thin-film designs and materials. This filter is a “first surface” hard oxide thin-film and is much more durable and long lived than laminated “soft film” designs used by several famous makers. They are also much less prone to the internal reflectance problems that plague laminated filters. Laminated filters can produce a very undesirable “doubling” of stellar images often with one of the doubles being red. Contrary to popular belief, this image doubling is not due to the red sideband component that many nebula filter designs produce, but in many cases is due to laminated glass not being exactly parallel to the protective cover plate after lamination. Many laminated filters display this annoying characteristic.

This filter averages around 1% Transmission (optical density of 2) through the rejection region from 540 to 590nm, and average transmission greater than 90% Transmission in the passbands, and greater than 75% at the 656.3nm H-Alpha line. The design yields a filter with a very symmetrical shape and high optical throughput, for maximum enhancement of nebula with a minimum of loss of stars in the field of view.

The substrate is quartz and has measured total wavefront values of .5 waves. The combination of first surface optical thin-film technology and a polished, flat substrate enables this filter to be used with high magnification, a real plus for small planetary nebula.

Image is representative of available filters.