There may be several factors influencing the consistent appearance of a certain object or phenomenon when you focus your telescope. Here are some key considerations:
Optical Alignments: Check the alignment of your telescope’s optics. Misaligned mirrors or lenses can cause images to appear incorrectly or result in recurring visual artifacts.
Atmospheric Conditions: Atmospheric turbulence, light pollution, or obstructions can impact what you see. It’s common for local atmospheric conditions to repeatedly affect your view in predictable ways.
Telescope Settings: The settings of your telescope’s focus may not be optimized for the observed object. Make sure you’ve adjusted the focus and other settings like aperture and magnification appropriately for your target.
Consistent Position: You might be focusing on a familiar celestial body, such as a bright star, planet, or even a satellite. These objects can consistently appear depending on the time of observation and your geographic location.
Internal Reflections: Internal reflections within the telescope’s optics can create ghost images or flares. Ensure that your optical components are clean and well-maintained to minimize these effects.
Temperature Effects: Temperature differences can cause tube currents or thermal expansion in the optics, affecting the focus and image quality. Allow your telescope time to equilibrate with the outdoor temperature.
Identifying the exact cause requires observing under different conditions and adjusting your equipment, but by systematically addressing these factors, you should be able to resolve or better understand the recurring sight you experience.