Lunt LS50THa H-Alpha Solar Telescope - Standard Kit

50mm Objective: The Sweet Spot for Solar Viewing

The 50mm precision-polished objective lens provides the ideal balance between light-gathering power and sensitivity to atmospheric seeing. Under typical daytime conditions, this aperture resolves fine details in sunspot umbra and delicate filamentary structures without being overly compromised by turbulence. The 350mm focal length (f/7) creates a full-disc view of the sun with low-power eyepieces, while still having enough image scale for satisfying high-magnification views of active regions.

Internal Etalon with Doppler True Pressure Tuning

At the heart of the LS50THa is its internal, unobstructed Fabry-Pérot etalon. By placing the etalon inside the telescope body, Lunt protects the critical component from damage and ensures thermal stability. The single etalon provides a narrow <0.6Å bandpass, which is the specification required to resolve high-contrast details against the bright solar disc.

Lunt’s Doppler True Tuning system uses air pressure to make fine adjustments to the etalon's bandpass. Unlike mechanical tilt-tuning which can introduce off-axis aberrations, pressure tuning provides a uniform, consistent view across the entire field. This allows you to shift the filter's transmission window to track features moving at high velocity, like eruptive prominences or plasma flows around active regions, without any degradation in image quality.

B400 Blocking Filter for Visual Safety and Contrast

This Standard Kit includes the B400 blocking filter, housed in a 1.25" star diagonal. The blocking filter is a non-negotiable safety component, removing all harmful radiation outside the H-alpha line before the light reaches your eye. The 4mm aperture of the B400 is optimized for visual observation, providing a fully illuminated field of view for full-disc observation without any vignetting.

Simple and Effective Helical Focuser

Focusing is managed by a robust helical focuser. This simple, intuitive design is easy to use, especially when wearing gloves in colder weather. While it lacks the fine control of a dual-speed Crayford, the helical focuser provides a direct, backlash-free mechanism for achieving a sharp image, which is perfectly adequate for the visual magnifications this telescope is designed for. The trade-off for simplicity is that the eyepiece and any attached camera will rotate during focus adjustment.

Safe and Fast Solar Alignment with the SunLock Finder

The integrated SunLock sun finder makes aiming the telescope safe and effortless. This small internal projection system casts a tiny image of the solar disc onto a white screen. To align the telescope, you simply adjust your mount until the projected image is centered on the screen. This system entirely eliminates the danger and difficulty of trying to find the sun through the main scope or a traditional finder.

Observing a Hedgerow Prominence with the LS50THa

Center a large active region on the limb of the sun and insert a medium-power eyepiece, around 8mm to 12mm. As your eye adapts, you will see the bright, boiling texture of the chromosphere. Slowly turn the pressure tuning knob. The surface details will fade slightly as the bandpass shifts, and suddenly, fiery structures will leap into view off the limb.

A classic hedgerow prominence, which looks like a soft glow in a lesser instrument, resolves into a forest of fine, feathery plasma tendrils. With the LS50THa's pressure tuner, you can follow these structures as they arch and twist, sometimes seeing brighter knots of material that indicate areas of intense magnetic activity. This direct, real-time view of the sun’s violent atmosphere is what makes a dedicated H-alpha telescope an essential instrument.

Choosing Your Lunt 50mm Solar Telescope

Lunt offers several packages for the 50mm platform, each tailored to a specific use case. This Standard Kit is the ideal starting point for a dedicated visual observer.

• LS50THa Standard Kit (This Model): Features the B400 blocking filter and a helical focuser. It is the most affordable and portable package, perfectly matched for visual observation and getting started in H-alpha.
• LS50THa Enhanced Kit: Upgrades to a B600 blocking filter and a 10:1 Rack & Pinion focuser. The larger blocking filter is better suited for imagers using cameras with larger sensors, and the focuser provides more precise control, which is critical for photography.
• LS50THa Premium PLUS Kit: Includes the B600 blocking filter, R&P focuser, and an external LS50C double-stacking etalon. This configuration narrows the bandpass to <0.3Å, dramatically increasing surface contrast to make filaments and active regions appear almost three-dimensional. This is the ultimate package for the high-resolution observer or imager.