Optolong OIII Narrowband Telescope Filter – 36mm

OIII-CCD 6.5nm Deep Sky Imaging Filter:

This filter is an extra Narrowband OIII-CCD 6.5nm filter. It is designed for nebula observation allowing 6.5nm bandwidth of light centered on a wavelength of 500nm through, which corresponds to OIII emission lines, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).

OIII emits 495.9nm and 500.7nm and it is a blue-green colored filter. Many of images of planetary nebula and supernova remnants are taken only with H-alpha and OIII filters. They show great structural details, but have natural colors, looking like an RGB image.

Main Use and Performance

• Suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants
• Hubble look of images can be made by the combination of H-alpha, OIII-CCD and SII-CCD, such as the famous Pillars of Creation (M16 Eagle Nebula)

Features of the OIII Filter:

Technical Data

• Schott substrate material
• Thickness 2.0mm
• 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 500nm
• 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 26mm for 1.25-inch; 45mm for 2-inch)
• Aerometal Material
• Precise CNC Machining
• Sand Blasting Process
• Black Anodized Finish
• Extinction Treatment to Prevent Reflection
• Laser Engraving No Fading

• OIII 6.5nm CCD Deep Sky Imaging Filter
• 80% peak transmission