1.Optolong OIII Introduction
Optolong Narrowband OIII filter is designed for nebula observation allowing 18nm 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.
Suitable for viewing on bright nebulae like M42 Orion Nebula in heavy light pollution areas.
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 filter of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER DIRECTLY. You would be BLIND if you fail to observe the warning.
2. OIII Spectrum for Reference
How to read the chart?
▲The horizontal axis is the Wavelength in Nanometers(nm).
▲The vertical axis is transmission in %.
▲The RED line shows the transmission of the filter. The artifical emission lines are shown in ORANGE. And the emission lines from constellation are shown in GREEN.
3. OIII features
|Specifications||Applicable camera model||Applicable lens||Unit Price in US$|
4. Manufacturing Technology
⭐High-precision grinding and polishing to make sure the substrate parallelism is greater than 30" and the surface accuracy is better than λ/4 ;
⭐Purified water ultrosonic clearning is aim to effectively remove impurities and dust from the substrate surface.
⭐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; IAD not only consolidates membrane compactness, increases film firmness, but also changes vacuum coating material characteristics.
⭐Planetary rotation system offers precision and homegeneity of coating ensuring high value on transmission of pass-band and Optical density of off-band;
⭐Non-cementing optical substrate coating;
⭐Quality Control: each filters is examined by Spectrophotometer for spectrum characteristic, and Laser Interferometer for surface accuracy.
2019 NEW package
※Note：We are now in the transition from the old to the new packaging style, ship is random.
6. Optolong OIII Performance
I. NGC2244 Rosette Nebual (HOO, H-alpha=Red, OIII= Green, OIII=Blue)
Optolong OIII filter features 1 type:
★1.25"(1 1/4" mounted), 2" mounted for eyepiece