Banjo Fm7 chord (Double C)F minor seventh on the 5-string banjo: 0 1 3 3, and 4 more shapes

Frets, string 4 to string 1: 0 1 3 3 (open position)

1. String 4 (C): open, C
2. String 3 (G): 1st fret, index finger, A♭
3. String 2 (C): 3rd fret, ring finger, E♭
4. String 1 (D): 3rd fret, little finger, F
5. String 5, the short g: open, G, not in the chord

Sounds: C A♭ E♭ F  ·  Fm7 is F, A♭, C, E♭ (1 · ♭3 · 5 · ♭7)

The 5th string: the short g rubs against the A♭ in this shape, a semitone away: some players let it ring, some skip it.

Double C tuning: gCGCD, the short 5th string first, then strings 4 to 1.