Optolong OIII Filter Visual - 1.25" Mounted

Optolong OIII Filter - 1.25'' Mounted

Narrowband OIII filter is designed for nebula observation allowing 18nm bandwidth of light centered on wavelength of 500nm through, which corresponds to OIII emission lines, and reducing the transmission of certain wavelengths of light

OIII are rich in Emission nebula or planetary nebula. This filter works well with Nebula like Orion, Eta Carinae, Lagoon, Owl nebula, Veil nebula and much more

Unlike photographic filter, visual filter have larger bandpass to allow much more light passing thru yet cut of significantly more light pollution than just UHC filter alone

Please note some nebula are rich in Ha or Hb Spectrum these recommended to use UHC or Hb filter instead

Transmission Exceeding 90% In 500nm Bandpass (OIII) range

Main Use and Performance

• Suitable for visual observation on most emission nebulae, planetary nebulae and supernova remnants
• Suitable for viewing on bright nebulae like M42 Orion Nebula in heavy light pollution
• Use with a large aperture telescope under clear and dark viewing conditions with good seeing
• Narrowband filter do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, not brightening the nebula.
• WARNING: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.

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
• 90% transmission at major OIII line 495.9nm and 500.7nm
• Precision off-band blocking, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm)

Coating Parameter

• 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”; 45mm for 2”)
• Aerometal Material | Precise CNC Machining | Sand Blasting Process | Black Anodized Finish | Extinction Treatment to Prevent Reflection | Laser Engraving No Fading

Package

• Plastic PP Case | Imported High Pressure EVA Case Lining | Silver Cardboard Box | High Density Sponge Carton Lining

Size

• Standard 1.25” & 2” | Round 36mm Unmounted

Spectral Curve

• The Major Emission Lines of Nebulae
• H-β486.1nm OIII 495.9nm OIII 500.7nm H-α656.3nm
• The Major Emission Lines of Artificial Light Pollution
• Hg 435.8nm 546.1nm 577nm 578.1nm
• Na 598nm 589.6nm 615.4nm 616.1nm