Chroma I-Bessell photometric filter - 2″ Mounted

Photometric Chroma I-Bessell filter

Visit Chroma I-Bessell photometric filter is designed to capture the near-infrared spectral band (approx. 700-900 nm) for UBVRI photometric studies. It is ideal for scientific observations and advanced astronomical imaging, enabling measurement of the brightness and colors of stars, galaxies and other celestial objects. Conforming to Johnson-Cousins/Bessell standards, this filter guarantees accurate, reproducible results, compatible with historical databases.

Key features

• Spectral transmission:
  • Focused on the near-infrared (I) band, with high transmission in the 700 to 900 nm range.
  • Effective blocking of distant UV and IR wavelengths to avoid spectral interference.
• Sustainable construction:
  • Multi-layer anti-reflective coatings to minimize halos and stray reflections.
  • Standard 2 mm thickness, compatible with most filter wheels and optical systems.
  • Parfocal with Chroma's other UBVRI filters, eliminating the need for refocusing.
• Compatibility:
  • Works perfectly with modern CCD and CMOS cameras, even on high-speed telescopes (f/1.8 to f/4.0).

Bessell filter technology and application

Bessell filters are a standard in astronomical photometry, designed to faithfully reproduce the characteristics of Johnson-Cousins filters while being adapted to modern CCD/CMOS sensors. Unlike the tinted glass filters used historically, modern Bessell filters use advanced dielectric coatings that offer stable transmission and excellent durability.

The I-Bessell filter is specially designed to capture near-infrared light, essential for the study of cool stars (such as red dwarfs), evolved stars (red giants) or even for analyzing distant galaxies where the redshift shifts their light into this spectral band. It also enables precise measurement of magnitude in this band, and calculation of color indices such as g'-r'These are crucial for characterizing the physical properties of celestial objects.

Applications

• Scientific photometry (UBVRI):
  • Precise measurement of brightness in the near-infrared band.
  • Study of variable stars, supernovae, star clusters and galaxies.
• Advanced astrophotography:
  • The perfect complement to other UBVRI filters for producing scientifically calibrated data sets.
• Astronomical research:
  • Detailed spectral analysis of cold stars, red giants and distant galaxies.

Conclusion

Visit Chroma I-Bessell photometric filter is an indispensable tool for amateur or professional astronomers wishing to carry out precise photometric studies in the near-infrared band of the spectrum. Its robust design, optimized transmission and rigorous calibration make it an essential choice for scientific imaging and advanced astronomical observation.