Chroma Technology SII 5 nm Filter, 1.25" Mounted
Chroma Technology SII 5 nm Filter, 1.25" Mounted
This S-II filter from Chroma Technology is a 5 nm, narrowband filter mounted and threaded for 1.25" eyepieces. It is centered on the spectral emission of singly ionized sulfur, common in nebulae. The emission is at two lines occurring as a doublet at 671.6 and 673.1 nm. This filter also separates sulfur emission from H-Alpha emission (656.3 nm).
Chroma manufactures astronomy filters with durable, sputtered hard coatings using single substrates of the highest quality glass, eliminating the need for laminations. Primary filter coatings are applied on the front surface and anti-reflection coatings on the rear to prevent ghosting and to maximize transmission.
Precise and accurate, the passbands of these filters remain spectrally stable and do not drift in response to extreme temperature fluctuations or changes in humidity.
All Chroma filters may be used with focal ratios of f/4 or smaller. Chroma astronomy filters are coated on 3.0 mm thick substrates and are parfocal with all other Chroma astronomy filters, except the LoGlow Light Pollution Filters.
Manufactured in Vermont.