Test image, 4 x 20 minutes, Apogee U8300 through APM115/805, Astrodon 3nm Ha filter.
Dark subtracted, levels and curves in Photoshop. No flats.
Guided using Astrodon MOAG and Meade DSI Pro II, with 1.5x barlow.
Guide error in RA is pretty apparent, and all four subs had oval stars. Coma / field curvature is also apparent in the corners.