Common imaging train

ASI2600MC Pro + M42 filter drawer + dual-band filter

The Flat6AIII is adjustable: dial its helical ring to William Optics' per-telescope figure and build the standard 55 mm behind the M48×0.75 T-mount thread. One-shot colour usually runs a single dual-band filter in a drop-in drawer instead of a wheel. The M42 drawer threads straight onto the camera and leaves a gap that one of the extenders in the camera box closes — once the filter glass is accounted for. Set the William Optics ring to your telescope and build the rest behind the M48 thread.