Altair 2" Solar Continuum Filter

(Solar Contrast Booster, 540nm)

• Bring the photosphere to life. The Altair 2" Solar Continuum filter sharpens the view of sunspots, granulation, and fine photospheric detail, turning a plain white disk into a textured, living surface.
• One narrow green band, maximum contrast. The filter blocks UV, IR, and the rest of the visible spectrum, passing only a tight 8nm FWHM band centered on 540nm, so solar features jump out whether you're observing by eye or imaging with a color or mono camera.
• Catch the granulation in motion. Granulation cells are fast-developing convection cells on the Sun's surface, and the boosted contrast helps you capture them, along with the intricate structure around sunspots, during those fleeting moments of steady seeing.
• Why 540nm matters. Green around 530-540nm is the traditional design benchmark wavelength for most telescope optics and the interferometry gear used to test them, and it's also where the human eye is most sensitive. Isolating it lets your scope work right at its sweet spot.
• A perfect match for achromats and ED doublets. Fraunhofer achromatic refractors and short focal length ED doublets peak in this green band by design, and most ED triplets and APOs do too, so the filter helps nearly any refractor deliver its best solar performance.
• Works with just about any telescope design. Refractors, Newtonians, Maksutovs, Dall-Kirkhams, Cassegrains, and SCTs all benefit from the improved contrast and sharper solar detail.
• Camera-friendly by nature. Most color and mono CMOS sensors peak in sensitivity and resolution in green, and color cameras with an RGGB layout devote two green pixels for every red and blue one, giving you a real resolution advantage at 540nm.
• Quality optics, built to last. A 1.85mm optical glass element polished to λ/4 with 30 arcsec parallelism is protected by a hard SiO2 overcoat, UV/IR blocking from 300-1100nm, and anti-reflection coatings, all housed in a standard 2" aluminium cell.
• Easy to add to your imaging train. The M48x0.75 thread screws directly into a 2" camera nosepiece, such as the Altair Hypercam 2" nosepiece, or into an Altair Magnetic Filter Holder with a 2" filter slider (MAGF series, choose the threads that match your camera).
• Designed to pair with a proper solar pre-filter. The filter is highly recommended for use with the Altair Imaging-Ready Herschel Wedge or Baader Solar Film.
• IMPORTANT SAFETY INFORMATION: Never use this filter for direct solar observation. It must always be used together with a professional full-aperture solar filter or a Herschel Wedge with a maximum transmission of 0.024% placed BEFORE this filter. Using it without a suitable solar pre-filter will permanently damage your eyes or camera.
• Reflecting telescopes: Fit Baader solar film over the front of the telescope, then screw the filter into a filter holder, camera, or eyepiece.
• Refractors: Use a Herschel Wedge and position the filter just in front of the camera or eyepiece. Never insert the filter before the Herschel prism, or it will melt.

Specifications

• Filter Type: Solar Continuum / Solar Contrast Booster
• Filter Size: 2"
• Thread: M48x0.75 (standard 2" filter thread)
• Cell Material: Aluminium
• Center Wavelength (CWL): 540nm
• Bandwidth (FWHM): 8nm
• Peak Transmission: 90%
• Glass Thickness: 1.85mm optical glass
• Surface Accuracy: λ/4
• Parallelism: 30 arcsec
• Coatings: SiO2 hard overcoat, UV/IR block 300-1100nm, anti-reflection coating
• Required Pre-Filter: Professional solar filter (e.g. Baader Solar Film) or Herschel Wedge, max. 0.024% transmission
• Compatible Optics: Refractors, Newtonian reflectors, Maksutovs, Dall-Kirkhams, Cassegrains, SCTs

What's in the Box?

• Altair 2" Solar Continuum Filter (540nm, 8nm FWHM) x1

Note: A professional solar pre-filter or Herschel Wedge is required for safe use and is sold separately.