Optolong 36 mm Narrow Band Filter Set H-Alpha, O-III, S-II for Astrophotography

Optolong Narrowband Filter Set

The Optolong SHO-3nm filter set contains SII 3nm, H-Alpha 3nm, and OIII 3nm narrowband filters that are typically used with astronomical monochrome cameras and modified DSLR cameras.

The extra narrowband SII 3nm filter is designed for observing nebulae and passes a bandwidth of 3nm centered at a wavelength of 672nm.

The H-Alpha 3nm filter is a popular narrowband filter that passes a bandwidth of 3nm at a wavelength of 656nm. Better choice of narrowband H-Alpha astrophotography filter for highest contrast and to detect fine nebular detail.

The extra narrowband OIII CCD 3nm filter has a bandwidth of 3nm, centered on a wavelength of 500nm, which corresponds to the OIII emission line. OIII emits 495.9nm and 500.7nm and is a blue-green color filter. Many images of planetary nebulae and supernova remnants are taken with only H-alpha and OIIII filters. They show great structural detail, but have natural colors and look like an RGB image.

The filters reliably block certain wavelengths of light, especially those produced by artificial light, including mercury vapor and high- and low-pressure sodium lamps, as well as unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e., skyglow).

Which side of the filter needs to face towards the telescope?

Optolong has a good explanation on their page with a check on unmounted filters. With mounted filters, it´s easy. The side with the external thread must face the camera.

Link to iOptron page: Should Optolong filters be installed in a certain orientation? (external link)
You can download the generated PDF from our own server.