Lunt LS60FHa: 60 mm H-alpha solar filter

The Lunt LS60FHa is a 60-mm H-alpha solar filter with no central obstruction and adjustable tilt. It can be used as part of a compatible Lunt system in a double-stack configuration or mounted on a compatible refractor with the appropriate adapter. This version is sold without a blocking filter, which is essential for solar observation.

Observing the structures of the solar disk

The double-stack configuration combines two filters in the same optical path. It is particularly suited for observers who wish to better distinguish filaments and active regions on the solar disk. According to Lunt, this combination enhances the contrast of surface structures while reducing overall brightness. The choice between single and double filtration therefore also depends on the details one is seeking: prominences generally appear brighter with single filtration.

Filtration Monitoring

The quality of the filtration depends on the performance of the optical assembly. Lunt explains that the tolerances of the etalon, the blocking filter, and the other components interact with one another. The manufacturer inspects the optical surfaces using interferometry and characterizes the standards with a monochromator. These measurements focus in particular on the position of the transmission band and its spectral width—two criteria that are useful for understanding the role of an H-alpha filter.

Putting Together a Complete Solar Kit

To convert a telescope into a solar instrument, the front eyepiece must be paired with a suitable Lunt solar filter. The filter is installed at the rear of the instrument and is an integral part of the safety system. You must check the telescope’s focal length, mechanical assembly, and observation configuration before selecting components. A front-mounted filter used alone does not constitute a safe system for viewing the Sun. Lunt also advises against using these front-mounted filters on lenses whose elements are spaced apart by oil.

Features of this version

The LS60FHa is part of the new generation of standards introduced by Lunt. Its specified bandwidth is 0.4 Å; the manufacturer states that it is less than 0.28 Å when used in a compatible double-stack configuration. It is designed to be stored in a hard aluminum case with custom-fit foam inserts.

Technical specifications