ALTAIR ASTRO 7nm - 540nm Continuous 1.25 V3" Solar Contrast Booster Filter

The Altair 1.25" Solar Continuum (version 3) solar filter is designed to enhance sunspots, fine details and the granular structure of the photosphere with exceptional contrast.

This filter acts as a Solar Contrast Booster, isolating a narrow 7 nm green band centered at 540 nm, where both the human eye and most CMOS cameras are at their most sensitive. The result is sharper, more nuanced images of the Sun's surface, especially around sunspots and convective cells.

Made with λ/4 optical glass and 30" parallelism, it features UV/IR blocking coatings from 200 to 1250 nm, 97.5% average transmission, and OD5 (0.001%) blocking of unwanted wavelengths. Blackened edges and "Reflex Blocking" anti-reflection treatment eliminate halos and internal reflections, further enhancing contrast.

Ideal for use in conjunction with a solar pre-filter such as Baader Solar Film or a Herschel wedge, the filter should be placed after these elements, just in front of the camera or eyepiece. It should never be used as the sole solar filter element.

⚠️ Safety Warning: This filter should not be used for direct solar observation without a suitable pre-filtering system (Baader Solar Film or Herschel wedge). Using it without protection may cause permanent damage to eyes or equipment.

The Altair 1.25" Solar Continuum is compatible with most telescopes - refractors, reflectors, Maksutov, Cassegrain or Schmidt-Cassegrain - and is especially recommended with achromatic and ED refractors, whose optimum performance is centered at the green wavelength. It also takes advantage of the higher sensitivity of CMOS cameras in the green channel, improving resolution in solar captures.

Technical specifications:

• Standard 1.25" thread in aluminum cell.

• Band: CWL 540 nm - Transmission: 97.5% - FWHM: 7 nm.

• Optical glass: 1.85 mm thick, λ/4, 30" parallelism.

• SiO₂ hard coating with UV/IR blocking (200-1250 nm) and anti-reflection.

• Compatible with Herschel wedges and Altair GPCAM and Hypercam Imageators (with adapter or magnetic filter holder).

The Altair Solar Continuum 1.25" is the perfect choice for advanced solar astrophotography, offering extremely high contrast images and guaranteed safety when used with the right equipment.