Banjo G7 chord (Open D)G seventh on the 5-string banjo: 0 1 2 3, and 5 more shapes

Frets, string 4 to string 1: 0 1 2 3 (open position)

1. String 4 (D): open, D
2. String 3 (F♯): 1st fret, index finger, G
3. String 2 (A): 2nd fret, middle finger, B
4. String 1 (D): 3rd fret, ring finger, F
5. String 5, the short f♯: open, F♯, not in the chord

Sounds: D G B F  ·  G7 is G, B, D, F (1 · 3 · 5 · ♭7)

The 5th string: the short f♯ rubs against the G and F in this shape, a semitone away: some players let it ring, some skip it.

Open D tuning: f♯DF♯AD, the short 5th string first, then strings 4 to 1.