I’m interested to hear from users who are doing larger lunar or solar mosaics, especially at longer focal lengths.
One issue I have been looking at recently is residual drift during longer lunar and solar imaging sessions. Many mounts provide standard Lunar and Solar tracking rates, but these rates are still approximations. The actual apparent motion of the Moon and Sun changes continuously with time and depends on the observer’s location.
For short captures, this may not matter much. However, even with perfect polar alignment, during larger mosaic projects, even a small mismatch in tracking rates can gradually show up as drift, framing inconsistency, or extra tweaks needed to keep each panel well positioned.
This is especially noticeable with the Moon, where the apparent motion is much faster and changes more significantly than the Sun’s. The standard lunar rate can reduce drift compared with sidereal tracking, but it does not fully follow the Moon’s true instantaneous topocentric motion.
I’m curious how do you handle this in practice when doing larger lunar or solar mosaics:
• Do you rely only on the mount’s Lunar or Solar tracking rate?
• Do you see drift during panel capture or between panels?
• Is tracking drift a noticeable issue for high-resolution mosaics at longer focal lengths?
One possible way to reduce this kind of drift is to use dynamically updated ephemeris-based tracking rates rather than relying only on a fixed Lunar or Solar tracking rate. I recently implemented this approach in HelioMaker as an optional feature called Dynamic Target Tracking, intended to work alongside SharpCap Pro. It continuously updates the mount’s custom RA and Dec tracking offsets based on the selected object’s real-time apparent topocentric motion. To be clear, HelioMaker is not currently fully integrated with SharpCap’s mosaic workflow to automate panel-by-panel mosaic capture. That is something I may consider adding in the future.
However, even in the current released version, Dynamic Target Tracking can improve the baseline tracking accuracy during lunar or solar mosaic imaging sessions. In practice, this can help reduce residual drift and keep the target more stable in the field during longer captures or manual/semi-automated mosaic workflows.
I would be interested to hear what others have experienced with large lunar and solar mosaics in SharpCap and other imaging software, and whether residual drift during mosaic work has been a noticeable limitation.
