Optolong Narrowband OIII Visual & Astroimaging Filter – 1.25 inch
Please note this is a 1.25 inch diameter round mounted visual & astroimaging filter to fit directly to all standard 1.25 inch telescope diagonals & CCD 2 inch Colour Filter Wheels which are commonly used globally by nearly every major CCD Manufacturer globally.
This is a premier quality filter from premier specialist astronomy & astroimaging filter manufacturer Optolong.
OIII-CCD 6.5 nm Deep Sky Imaging Filter:
This filter is an extra Narrowband OIII 6.5 nm filter. It is designed for nebula observation allowing 6.5 nm bandwidth of light centered on a wavelength of 500 nm 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 495.9 nm and 500.7 nm and it is a blue-green coloured 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 colours, 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)
- Premier German 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
- 95% transmission at bandpass with the LRGB filters
- The filter has 80% transmission, the OIII line is 500 nm
- Precision off-band blocking
- 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
- Ultra-thin filter cell minimize vignetting by maximize possible clear aperture
- Aerometal Material
- Precise CNC Machining
- Sand Blasting Process
- Black Anodized Finish
- Extinction Treatment to Prevent Reflection
- Laser Engraving No Fading