Common imaging train

Sky-Watcher Evostar 80ED + 0.85× reducer + ASI2600MC Pro + filter drawer

The 0.85× reducer/corrector for the Evostar 80ED is a 55 mm M48 optic. 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. Sky-Watcher does not publish this corrector's image circle, so the APS-C corners are something to test, not assume.