Optolong Filters SHO 3nm 36mm (78310)

Optolong Filters SHO 3nm 36mm (Model 78310)

The Optolong SHO 3 nm filter set is a professional narrowband filter kit designed for advanced astrophotography. It includes three precision filters — H-alpha, OIII, and SII — each with an ultra-narrow 3 nm bandwidth to maximize contrast and isolate specific emission lines. These filters significantly reduce light pollution and unwanted wavelengths, allowing detailed imaging even under moonlight or in urban environments. The SHO combination enables the creation of dramatic tri-color images similar to those produced by space telescopes.

Narrowband filters enhance contrast by transmitting only very specific wavelengths that correspond to key spectral emission lines, such as hydrogen (H-alpha at 656 nm), oxygen (OIII at 500 nm), and sulfur (SII at 672 nm). Because they block nearly all other light sources, they are ideal for long-exposure photography and can be used even when the Moon is visible.

OIII Filter (3 nm)
This narrowband OIII filter transmits a 3 nm bandwidth centered at 500 nm, corresponding to doubly ionized oxygen emission lines. It blocks all other wavelengths, providing strong contrast for planetary nebulae and supernova remnants.

H-alpha Filter (3 nm)
The H-alpha filter isolates the 656 nm hydrogen emission line. It is one of the most popular narrowband filters for astrophotography, revealing fine structural details in emission nebulae and performing exceptionally well in light-polluted conditions.

SII Filter (3 nm)
The SII filter transmits light at 672 nm with a 3 nm bandpass. It is designed specifically for nebula photography and captures sulfur emissions often used to create the well-known “Hubble palette” effect in tri-color imaging.

When combined, H-alpha, OIII, and SII filters allow astrophotographers to produce high-contrast, richly detailed images of emission nebulae, planetary nebulae, and supernova remnants. This tri-color narrowband technique can be performed even during bright lunar phases, ensuring more productive imaging sessions.

Mechanical and Optical Specifications
Filter size: 36 mm
Mount type: Unmounted
Mount material: Aluminum
Optical coating: Multi-layer, plane-parallel
Bandwidth (FWHM): 3 nm
Filter thickness: 2 mm
Number of filters included: 3

Type and Application
Type: Line filters (SHO set)
Suitable for astrophotography: Yes
Visually useful: Yes
Anti light-pollution capability: Yes
Suitable for nebulae and galaxies: Yes
Suitable for planetary nebulae: Yes
Suitable for supernova remnants: Yes
Suitable for hydrogen nebulae: Yes