The'Acuter 40 (Phoenix 40) offers excellent contrast, with a bandwidth of less than 0.6 Å, and becomes an 80-mm f/5 telescope for nighttime use; it cannot be used in a double-stack configuration. A complete Lunt kit, such as the LS40THa Premium With a double stack (less than 0.25 Å), it's built to last and evolve. Avoid old, used Coronado models: their filters degrade over time, and there's no way to verify this before purchase.
In three steps: first, focus on the edge of the disk; then, adjust the initial pressure for each standard separately; finally, fine-tune both together until you achieve the best contrast between the protuberances and the surface. The settings listed in the manual are only a starting point: they vary depending on temperature and the instrument.
Always place a certified filter in front of the lens, never on the eyepiece. The DayStar ULF-70 Fits instruments and objectives with an outer diameter of 65 to 89 mm. It shows sunspots; to observe prominences, an H-alpha telescope is required.
