Lunt LS40THa Premium Kit

40mm Dedicated H-Alpha Solar Telescope — Full DS Performance The LS40THa Premium Kit is the complete 40mm Lunt experience — the finest 40mm H-alpha solar telescope available anywhere, with double-stack performance that sets a benchmark no competitor in this aperture class can approach. At <0.25Å combined system bandpass in a 2.6-pound grab-and-go package, this instrument delivers professional-level chromospheric contrast that was, until recently, achievable only in much larger and more expensive systems. The LS40FHa double-stack filter adds a second 0.35Å tilt-tuned etalon to the optical path, working in series with the internal etalon to produce a combined system bandpass of <0.25Å. Two independently tunable etalons at the same specification — the combined FWHM is tighter than any single-etalon system in the 40mm class, and tighter than what the Acuter Phoenix 40 can achieve even in theory. The Acuter has no viable double-stack option: independent observers attempting DS with the Phoenix 40 documented reflections and tunnel effects that render the result unusable. The Lunt LS40THa Premium makes <0.25Å portable.   The 10:1 dual-speed R&P focuser — a step above the 1:1 unit in the Enhanced — provides the micro-adjustment capability that sub-quarter-angstrom observing demands. At <0.25Å bandpass, the difference between optimal and slightly off-optimal tuning is visible in the image. The dual-speed mechanism lets you course-adjust quickly and fine-adjust with precision, staying on the exact position that reveals the most detail. The 7.2–21.5mm zoom eyepiece covers the full magnification range from 19x full-disk surveys to 56x active region detail in a single twist — critical when conditions are variable and solar features are evolving faster than eyepiece changes allow.   The 6" Vixen dovetail provides the extended rail length needed to balance the system with the DS filter in place. The B600 blocking filter handles imaging. Every unit individually assembled and individually verified. At $1,795, the Premium is $440 more than the Acuter Phoenix 40 — delivering complete double-stack performance the Acuter cannot match at any price — and delivers <0.25Å double-stack performance against the Acuter's single-stack 0.6Å. The comparison does not require further comment.   KEY SPECIFICATIONS Aperture 40mm, full unobstructed Focal Length / Ratio 400mm f/10 Etalon System Dual front-mounted tilt-tuned: primary + LS40FHa double-stack Bandpass (Single Stack) <0.35Å — individually verified Bandpass (Double Stack) <0.25Å combined system — two 0.35Å etalons in series Blocking Filter B600 — 6mm clear aperture, imaging ready Focuser 1.25" CNC R&P 10:1 dual-speed, integrated brake, rotatable, 6–8 lb capacity Eyepiece 7.2–21.5mm zoom — 7 elements, 15mm eye relief, 0.1% AR (19x–56x) Finder SunLock red dot finder Dovetail 6" Vixen-style (extended for DS filter balance) Case Aluminium hard case with custom foam insert Weight ~2.6 lbs OTA + LS40FHa DS filter (~1 lb) Night Use Dedicated solar — daytime use only