Skip to content
IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
IMPORTANT: Our store is located in Canada. All orders that include products manufactured outside of Canada or USA will be subject to tariffs and duties, regardless of the order value. US customers are responsible for all applicable duties and tariffs, and those will be billed by the carrier, except for the Lacerta upgrade kit, for which we collect them at checkout.
Lunt 40mm Double Stack Solar Filter for LS40THa

Lunt 40mm Double Stack Solar Filter for LS40THa

by Lunt Solar Systems
SKU LSS-LS40FHa
$695.00 - $695.00
$695.00
$695.00 - $695.00
$695.00
Price Match Policy!
  • Double-stack upgrade for Lunt LS40THa telescopes
  • Reduces system bandpass to <0.29Å
  • 40mm clear aperture
  • Front-mounted, tilt-tuned etalon
  • Reveals high-contrast chromospheric detail
1 in stock
FREE Shipping in CONUS
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Lunt 40mm Double Stack Solar Filter for LS40THa

    The Lunt 40mm Double Stack Solar Filter is the definitive contrast-enhancing upgrade for your LS40THa telescope, adding a second 40mm front-mounted etalon to slash the system's final bandpass to an exceptionally narrow <0.29Å. By placing two precision etalons in series, this filter dramatically increases contrast on solar surface features, transforming the Sun from a flat disk into a dynamic, three-dimensional sphere.

    Double-Stacking the LS40THa for <0.29Å Bandpass

    This filter adds a second, perfectly matched 40mm etalon to the front of your existing LS40THa solar telescope. The two filters working in series create a combined system bandpass of less than 0.29Å — the tightest available in any Lunt double-stack configuration. Installation is simple, requiring no tools or a return to the factory, allowing you to upgrade your view in minutes.

    Revealing High-Contrast Chromospheric Detail at <0.29Å

    The significant bandpass reduction is not just a number; it translates directly to a stark increase in visible surface detail. With the LS40FHa installed, the solar chromosphere is rendered with striking clarity. Plage boundaries sharpen into cellular networks, dark filaments reveal their multi-strand internal structure, and the delicate threading within solar prominences becomes visible from base to tip.

    Standalone H-Alpha Filtration and Critical Safety Requirements

    While designed as an upgrade for the LS40THa, the LS40FHa can also serve as a primary H-alpha filter for a compatible customer-supplied refractor. However, for safe operation in any configuration, a Lunt blocking filter is mandatory. The LS40FHa etalon alone is not a complete safety device and must be paired with an appropriate blocking filter to prevent irreversible eye damage.

  • How do I install the Lunt 40mm Double Stack Filter on my LS40THa?

    Installation is straightforward and requires no tools. The LS40FHa filter simply threads onto the front objective of your existing Lunt LS40THa telescope.

    What is the main visual benefit of double-stacking my LS40THa?

    The primary benefit is a dramatic increase in surface contrast. The tighter <0.29Å bandpass makes features like filaments, plage, and granulation "pop" against the solar disk, revealing details that are subtle or invisible in a single-stack system.

    Can I use the Lunt LS40FHa filter on a telescope other than the LS40THa?

    Yes, it can be used as a standalone H-alpha filter on a compatible refractor. However, you must pair it with a correctly sized Lunt blocking filter for safe solar observation. The etalon by itself is not sufficient for eye safety.

    Is a blocking filter included with the Lunt 40mm Double Stack Filter?

    No. This filter is designed as an add-on for the LS40THa telescope, which already includes a blocking filter. If you plan to use this on a different telescope, a separate Lunt blocking filter is required and must be purchased separately.

    Will this Lunt 40mm filter show more solar prominences than my single-stack LS40THa?

    It will not necessarily show more prominences, as they are often bright enough to be seen in a single-stack view. However, the double-stacked view at <0.29Å will reveal significantly more internal detail, structure, and texture within those prominences, which often appear as uniform shapes in a wider bandpass.

    How does the LS40FHa achieve such a narrow bandpass compared to other Lunt systems?

    The LS40FHa achieves its exceptionally narrow <0.29Å bandpass by placing two front-mounted, tilt-tuned etalons in series. This specific configuration results in a tighter combined bandpass than Lunt systems that pair a front-mounted filter with an internal, pressure-tuned etalon.

  • SKU LS40FHaP
    Aperture 40mm
    System Bandpass (Double Stacked) <0.29Å
    Etalon Type Front-Mount, Tilt-Tuned
    Telescope Compatibility Lunt LS40THa Series

    • 40mm Double Stack Solar Filter

      × 1

  • Lunt Solar Systems 5-Year Warranty