36mm OIII 6.5nm Filter Optolong

36mm OIII 6.5nm Filter Optolong

Extra Narrowband OIII 6.5nm Filter designed for nebula observation with 500nm wavelength, that corresponds to the OIII emission lines. Reduces the transmission of certain wavelengths of light, particularly those produced by artificial lights, including mercury vapor, both high and low pressure sodium vapor lamps and unwanted natural light caused by the emission of neutral oxygen into our atmosphere (e.g. Skyglow).

The OIII emits from 495.9nm and 500.7nm wavelength so that it features a blue-green color. Many images of planetary nebulae and supernova remnants are taken only with H-ALPHA and OIII filters; Enables to show great structural details while maintaining natural colors, the image thus shot looks like an RGB image.

Utilization and Performance

Suitable for viewing most emission nebulae, planetary nebulae and supernova remnants.

Narrow band imaging can be achieved by combining filters of the SHO set (H-ALPHA, OIII, SII), this will further help achieve a clear image even in heavy light pollution conditions.

The OIII filter does not eliminate the effects of light pollution and does not increase the brightness of the object being shot, but rather increases the contrast between the nebula and the night sky, making image processing easier.

This Narrow-band 6.5nm OIII Filter is designed to be attached to filter wheels, to filter drawers or, only for mounted filters, directly on DLSR cameras.

Technical Specifications

Technical Data

• Schott substrate material
• Thickness 2.0 mm
• Surface Quality: 60/40 (Refer to MIL-O-13830)
• Fine-optically polished to ensure accurate 1/4 wavefront and <30 seconds parallelism over the both surfaces
• The OIII filter has an 80% transmission, the OIII line is 500 nm 
• Precision off-band blocking

Coating Parameter

• Multi-layers anti-reflection coating
• Non-cementing optical substrate coating
• Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change
• Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band

Filter Cell

• Ultra-thin filter cell minimize vignetting by maximize possible clear aperture (clear aperture is 26 mm for 1.25-inch; 45 mm for 2-inch)
• Aerometal Material
• Precise CNC Machining
• Sand Blasting Process
• Black Anodized Finish
• Extinction Treatment to Prevent Reflection
• Laser Engraving No Fading