A. About Optolong's LRGB FIlter Set

The Optolong LRGB Filter Set is designed for maximum contrast and with extremely high gradients for clear differentiation of colors. The LRGB filter set divides the spectrum into its components: red, green, blue and luminance.

The OIII emission overlaps on blue and green filters with maximum transmission to allow high efficiency and natural color imaging. The gap between green and red filters serves to block out the primary Sodium (Na) light pollution line at 589nm and improves color balance and separation.

B. Main Uses and Performance

• Works well with debayered monochrome CCD cameras.
• Suitable for deep sky and planetary CCD imaging.
• RGB imaging allows equal weighting factors for each channel which is very important for automated imaging.
• The ideal raw material for image processing in the sRGB color space is available with the LRGB filter set and a monochrome CCD camera.

C. Spectral Curve Transmission Characteristics

• 95% transmission at passband.
• High and precise blocking of offband.
• It also blocks out infrared wavelengths (700-1100nm) so a separate IR cut-off filter is not required for imaging applications.

D. Technical Specifications

• Both surfaces are fine optically polished, accurate to 1/4 wavelength or better, and parallel to within 30 seconds or arc.
• 2mm thick Schott B270 optical glass substrate material.
• Very high surface quality of 60/40 or better (US Military Spec MIL-O-13830).

E. Optical Coating Specifications

• Multi layer anti-reflection coated.
• 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) so that there is no deviation due to temperature changes during use.
• Precise and homogeneous coatings ensure high values of desired passband and blocking of unwanted offband.
• Every single filter is tested and passed by Optolong before shipping to dealers.

F. Other

• 1.25" astronomy filter with standard M28.5x0.6 male filter thread (no female thread, so it cannot be stacked with other filters).
• Ultra-thin filter cell to minimize vignetting; clear optical aperture of 26mm.
• Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, and laser engraving.
• High quality protective plastic storage case.

WARNING: Optolong filters are not designed for direct solar observation. NEVER use these filters for observing the Sun, or permanent eye and equipment damage will result.