Common imaging train

Takahashi FSQ-85EDX + RD 0.73× + ASI2600MC Pro + filter drawer

The FSQ-85EDX with the RD 0.73× reducer asks for a longer metal back distance than a refractor flattener — the extenders in a camera box do not reach it. 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. The reducer's metal back distance is well beyond 55 — expect to add a longer extension than the one in the box.