Lunt LS50THa H-Alpha Solar Telescope - Premium PLUS Kit

The 50mm f/7 Optical Foundation

The heart of the LS50THa is its 50mm f/7 singlet objective lens. This aperture provides a significant increase in resolving power over smaller 40mm scopes, rendering finer detail in solar prominences and the structure within sunspot umbrae. The 350mm focal length creates a manageable image scale that is well-matched to the included B600 blocking filter and zoom eyepiece, allowing you to frame the full solar disk or zoom in on active regions without needing Barlows.

Internal Pressure-Tuned Etalon for Uniformity

Inside the main optical tube lies the primary sub-aperture etalon, the core filtering engine of the telescope. Lunt's innovative pressure tuning system adjusts the air pressure within the etalon cavity, shifting the filter's bandpass with zero mechanical stress on the optics. This Doppler True Tuning method provides a more uniform view across the entire field compared to mechanical tilt-tuning, which can introduce bandpass variations and gradients from the center to the edge of the view.

Double-Stacking for a High-Fidelity Chromosphere

The Premium PLUS kit's defining feature is the included LS50C front-mounted double-stack etalon. Adding this second filter dramatically narrows the system's final bandpass from ~0.6Å to less than 0.30Å. This is not a subtle change; the reduction in out-of-band light significantly increases contrast on the solar disk, causing faint filaments, active region plage, and the mottled "orange peel" texture of the chromosphere to snap into sharp relief. While a single-stack system excels at prominences, this double-stack configuration is optimized for revealing the complex, three-dimensional surface of the Sun.

The B600 Blocking Filter: A Matched System

The blocking filter, housed in the star diagonal, is the final critical component in the safety chain. This kit includes the B600, with a 6mm aperture perfectly suited for visual observation and imaging with smaller-chip cameras. It provides a generous field around the solar disk at the native 350mm focal length, ensuring you never suffer from a vignetted or cut-off view of the Sun's limb and surrounding prominence activity.

Upgraded Focuser and Versatile Zoom Eyepiece

This kit moves beyond the helical focuser of the standard package to a more robust 1:1 Rack & Pinion focuser. This design is better equipped to handle the weight of cameras and multiple eyepieces without flexure, providing a more stable and repeatable focusing experience. Paired with the included Lunt Zoom eyepiece, you can move from a full-disk contextual view to high-magnification close-ups of an active region with a simple twist, maintaining focus and keeping your target centered.

SunLock Finder for Safe and Fast Alignment

Finding and centering the Sun without looking at it is the first challenge of any solar observation. The included SunLock is a purpose-built solar finder that projects a small image of the Sun onto a viewing screen. Simply center the dot on the screen, and the Sun will be in the eyepiece field of view, eliminating any guesswork and ensuring a safe, immediate start to your session.

An Observer's View: Filaments on the Grid

With the double-stack engaged and the pressure tuner dialed in, point the LS50THa at a large, snaking filament. At low power with the zoom eyepiece, it appears as a dark, irregular line against the brighter chromosphere. As you increase magnification, what was a simple line resolves into a structure with depth and texture. You can trace its path across the solar grid, noting the finer, thread-like extensions and anchor points that betray the powerful magnetic forces holding it in place against the Sun's surface. This is the view a <0.30Å bandpass makes possible.

System Trade-offs and Considerations

The principal trade-off for the enhanced surface detail of the double-stack system is a slight dimming of the image compared to the single-stack configuration. While prominences remain bright and clear, the double-stack view prioritizes disk contrast over limb brightness. The 50mm aperture provides excellent detail but may be more susceptible to poor atmospheric seeing than a smaller 40mm scope, which can sometimes provide a steadier, albeit less resolved, image under turbulent daytime skies.

Choosing Your Lunt 50mm Solar Telescope

Lunt offers the LS50THa in several packages, each designed for a specific observer. The Premium PLUS Kit represents the pinnacle of the 50mm line, offering the highest-contrast views and most complete accessory package.

• LS50THa Standard Kit: This is the entry point, featuring a single etalon (<0.6Å), B400 blocking filter, and helical focuser. It is an excellent choice for focusing purely on solar prominences, offering the brightest possible view of structures on the Sun's limb.
• LS50THa Enhanced Kit: This package upgrades the blocking filter to the B600 for a wider field of view and moves to the 1:1 Rack & Pinion focuser. It remains a single-stack system, making it a great option for those who want a better focuser and a more complete view of the disk but do not yet require the highest surface contrast.
• LS50THa Premium PLUS Kit: The subject of this page. By adding the LS50C double-stack filter, this kit achieves the narrowest bandpass (<0.30Å) for maximum chromospheric detail. It is the definitive choice for the serious visual observer or imager who prioritizes resolving filaments, plage, and granulation over all else.