Common imaging train

WO Flat 61A + ASI585MC Pro + filter drawer

The Flat 61A is the fixed 1.0× flattener for the Zenithstar 61 with a longer-than-55 mm spacing behind its 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. Another non-55 flattener: read the required figure, not the convention, before buying rings.