Where to capo for F# Dorian
Put the capo at fret 4 and play F# Dorian using D Dorian shapes. That is the easiest of the eight positions ranked below, and it is what most players reach for. Against playing F# Dorian open, it drops the mean difficulty of the key's seven chords from 4.4 to 3.4 and gains 9 ringing open strings.
You want F#. Capo 4 and play in D.
All eight positions, ranked
Each row transposes F# Dorian down by that many frets to find the shapes your hand would actually make, then scores the best voicing of all seven chords — fewer fingers, less stretch, closer to the nut, fewer muted strings. Lower is easier. Standard tuning (E2 A2 D3 G3 B3 E4).
What you are playing
The seven chords of F# Dorian are F#m, G#m, A, B, C#m, D#dim, E — the ones the ranking above is scored against. Their diagrams are on the F# Dorian key page.