Optolong 2" Filter Set with H-Alpha, SII, and OIII Filters

Optolong presents a 3-piece filter set designed to offer enthusiasts access to their premier deep-sky filters at a budget-friendly price. This set includes three 2" filters: the popular 7nm Hydrogen-Alpha, 6.5nm Sulfur-II, and 6.5nm Oxygen-III, each mounted in a 2" cell.

Crafted from Schott glass, all filters undergo multi-coating using ion-assisted deposition technology, ensuring both scratch resistance and consistent central wavelength (CWL) stability. The filter housings are constructed from lightweight yet durable metal, precisely CNC machined, sand-blasted, black anodized, and laser engraved. This meticulous construction results in ultra-thin filter cells, each providing a clear aperture of 45mm.

Optolong 7nm H-Alpha Filter - The Optolong H-Alpha 7nm filter is a highly specialized narrowband filter designed to transmit a 7nm bandwidth of light centered at the 656nm wavelength, corresponding to the H-alpha emission line. It effectively suppresses wavelengths associated with both natural skyglow and artificial light pollution, including emissions from high and low-pressure sodium vapor and mercury vapor lights. This selective filtration enhances contrast, allowing astrophotographers to capture detailed and vivid images of H-alpha emitting nebulae, even under challenging lighting conditions.

Optolong 6.5nm SII Filter -

The Optolong Sulfur-II 6.5nm Extra-Narrowband Filter is specifically engineered for astrophotography, transmitting a narrow 6.5nm bandwidth of light centered at the 672nm wavelength. This design effectively suppresses unwanted light from both natural sources, such as atmospheric skyglow, and artificial sources, including mercury vapor and high- and low-pressure sodium vapor lights. By doing so, it enhances the contrast of celestial images, making faint sulfur-emitting nebulae more discernible.

As with all Optolong filters labeled “CCD,” this SII filter also blocks infrared wavelengths ranging from 700nm to 1100nm, eliminating the need for an additional IR-cut filter. This feature ensures that only the desired spectral lines are captured, improving image clarity and detail.

Optolong 6.5nm OIII Filter - The Optolong Oxygen III (OIII) 6.5nm Extra-Narrowband Filter is specifically designed for astrophotography, transmitting a narrow 6.5nm bandwidth of light centered at the 500nm wavelength. This corresponds to the OIII emission lines at 495.9nm and 500.7nm, which are prominent in many nebulae. By allowing only this specific range of light to pass through, the filter effectively suppresses unwanted wavelengths associated with both natural skyglow and artificial light pollution, including emissions from mercury vapor and high- and low-pressure sodium vapor lights.
 

As with all Optolong filters designated as “CCD,” this OIII filter also blocks infrared wavelengths ranging from 700nm to 1100nm, eliminating the need for a separate IR-cut filter. This feature ensures that only the desired spectral lines are captured, enhancing image clarity and detail.TelescopesPlus

The filter is constructed using high-quality Schott glass and features multi-layer coatings applied through ion-assisted deposition technology. This process enhances scratch resistance and ensures stability of the central wavelength (CWL), even under varying temperature conditions.