When considering the purchase of a used 20″ Obsession telescope, it’s important to thoroughly evaluate both the optical and mechanical condition of the instrument. Here are key aspects to examine:
Optics Condition: Inspect the mirrors for any signs of scratches, dents, or coatings that might be deteriorated, such as cloudiness or discoloration. Make sure to ask if the mirrors have been recoated, and if so, when. A professional recoating can restore the reflective surface but be prepared for the associated costs if it’s needed.
Collimation: Check if the telescope maintains collimation well with regular use or if adjustments are frequently necessary. Poor collimation stability might indicate wear or misalignment issues with the focuser or other components.
Mount Stability: Investigate the condition of the Dobsonian mount, ensuring that its movements in altitude and azimuth are smooth and free from significant stiction or backlash. Look for wear in the Teflon bearings and ensure that all base components are sturdy and undistorted.
Structural Integrity: Evaluate the condition of the telescope’s truss tubes and connections. These should be free from dents and should lock securely into place to ensure overall rigidity. Any wobble in the structure could impact the viewing experience.
Age and Usage: Ask about the age of the telescope and how frequently it was used. A well-maintained telescope, even if older, might be preferable to one that was heavily used and not properly cared for.
Accessories: Determine what, if any, accessories are included with the sale, such as eyepieces, a finder scope, or a focuser. Additionally, check if any customizations were made by the previous owner, as these can either enhance or detract from the telescope’s utility.
Transportation and Setup: Confirm that all necessary components are included for transportation and easy setup, such as the rocker box, base, and all hardware. Check for the ease of assembly and if any additional tolls or steps are needed.
Documentation and Support: Inquire if the original documentation and user manuals are available, which can be invaluable for reference and troubleshooting. Additionally, community support for Obsession telescopes is strong, so consider engaging with user groups online.
Carefully evaluating these aspects can ensure you’re making a well-informed purchase and that the telescope meets your expectations for function and quality.