Lunt Front Mount 40mm Double Stack Solar Filter

Lunt Front Mount 40mm Double Stack Solar Filter - LS40FHa 

LS40FHa — 40mm Front-Mount Double Stack Solar Filter The double-stack upgrade for the Lunt LS40THa series. Two 0.35Å etalons in series — the tightest combined bandpass in the Lunt range.

Now with new-generation etalons — every unit individually tested on Lunt's precision metrology equipment. Every specification is verified, not estimated.

The LS40FHa is a 40mm aperture front-mounted tilt-tuned etalon designed for two purposes — as a double-stack upgrade for the Lunt LS40THa dedicated 40mm solar telescope series, or as a standalone H-alpha solar filter for a compatible customer-supplied refractor.

As a double-stack filter for the LS40THa: The LS40FHa adds a second 0.45Å etalon to the optical path, placing two etalons of equal specification in series with the LS40THa's own front-mounted etalon — delivering a combined system bandpass of <0.29Å. This is the tightest combined bandpass available in any Lunt double-stack configuration.

Because both etalons are front-mounted tilt-tuned at 0.45Å — rather than pairing a front-mount filter with an internal pressure-tuned etalon — the in-series result is tighter than larger double-stack systems. At <0.29Å, chromospheric detail that single-stack instruments at this aperture cannot resolve becomes visible: plage boundaries sharpen into cellular networks, filaments reveal dark cores and multi-strand structure, and prominences show internal threading from base to tip.

As a standalone H-alpha filter for customer refractors: The LS40FHa can be used on a compatible customer-supplied refractor as a standalone front-mounted H-alpha filter. A Lunt blocking filter must be used at all times — this is a safety requirement.

If you are looking for a complete standalone package including a blocking filter and adapter, Lunt offers complete front-mounted filter packages that include both at:
luntsolarsystems.com/collections/front-mounted-etalon-systems

Installation requires no tools and no factory visit. A Lunt blocking filter is required for safe operation — the LS40FHa is not a standalone safety device.

Features:

• 40mm Front-Mount Design – Features a 40mm unobstructed optical aperture, purpose-built for the Lunt LS40THa series.

• Precision 0.45Å Etalon – Includes a tilt-tuned 0.45Å etalon individually verified using Lunt’s precision metrology equipment.

• <0.29Å Combined Bandpass – Uses two 0.45Å tilt-tuned etalons in series to achieve a combined system bandpass of less than 0.29Å.

• Enhanced Solar Detail – Reveals fine chromospheric structures, including sharper plage boundaries, dark filament cores, multi-strand filaments, and detailed prominences.

• Dual-Purpose Compatibility – Works as a double-stack upgrade for LS40THa telescopes or as a standalone H-alpha filter for compatible customer-supplied refractors.

• Lightweight & Portable – Weighing approximately 1 lb (0.4kg), the LS40FHa is easy to transport and includes an optional aluminium hard case with fitted foam for convenient storage and protection.

What's Included:

✓ Lunt Front Mount 40mm Double Stack Solar Filter

✓ Instructional Manual

Specifications: