Common imaging train

WO Flat68III + ASI2600MC Pro + filter drawer

The Flat68III is the 1.0× flattener for the GT/Zenithstar range: set its ring to your telescope and build 55 mm behind the M48 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. Native focal length, 55 mm spacing, one drawer: the simplest William Optics colour train.