Common imaging train

WO Flat 8 (0.72×) + ASI2600MC Pro + filter drawer

The Flat 8 is a 0.72× reducer at the standard 55 mm behind its M48 thread, for the GT/FLT range. 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. 0.72× makes a fast system, and fast systems are where the drawer's M42 output starts to clip the APS-C cone.