A. About Optolong's UV-IR Cut FIlter
Optolong's UV-IR cut filter is designed to block ultraviolet and infrared wavelengths to improve sharpness of the image as most of the optics are designed for the visible spectrum, because it's very difficult to create a lens with the same focal point for the visible and IR spectrum. It is used on a digital camera and the video, which do not have an IR protection filter toward an image sensor or were remodeled. This is important because unfiltered CCD and CMOS sensors are extremely susceptible to UV and IR rays just outside the visible spectrum that can have a very negative impact on image quality.
B. Main Uses and Performance
- Suitable for color CMOS and CCD cameras and modified DSLRs.
- Use with monochrome CCD for astrophotography.
C. Spectral Curve Transmission Characteristics
- 95% transmission at visible spectral region 420-680nm highly passing the major nebula emission lines of H-Alpha 656nm, SII 672nm and NII 654nm and 658nm.
- Ultraviolet 300-400nm and infrared wavelength 700-1100nm cut-off.
- 0.1% transmission of ff-band wavelengths.
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.
- 2' astronomy filter with standard M48x0.75 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.