HOLDING HIS MANDOLIN CASE, the young man queried, "Ah just want t'know one thing, how do you know where to put your fangers?" This is a very good question; and as in catskinning, there are usually several different answers. With one, two, or sometimes even three locations on the mandolin fretboard for any given note, and any one of four fingers of the left hand to use, there can be as many as 12 different ways for fingering any given fretted note.
The reach of the left hand is assumed to extend (with a hearty stretch of the pinky) approximately eight frets at a time. Thus, any notes which fall between the open fourth string and the 8th fret of the first string may be reached in the first, or open position. To reach all the notes above this fret, or in order to phrase properly, a displacement, or shift, of the left hand is necessary. Thus, if the left hand is placed so that the first finger falls on C we have the second position; if the first finger falls on D we have third position; if it falls on E we have the fourth position, and so on.
In playing any piece of music, written or improvised, there are usually several approaches to fingering, even when the range of the piece is safely lodged within the confines of the first position. Given the fact that these different fingering options exist, it behooves us to seek out the most convenient (easiest to play) ones. This will become more apparent, and more necessary, when we try to play tunes or passages of greater difficulty, like bebop heads (melodies) or Paganini caprices! In classical music (particularly music for violin), fingerings are often indicated; but it's good practice to get in the habit of figuring out your own.
First, try playlng the major scales below (F, G, and A) in the closed second, third, and fourth positions (see Ex. 1).
To illustrate position shifts, I've selected a passage from the introduction to my composition "Opus 57 In G Minor" (as recorded on the album The Dauid Grisman Quintet [Kaleidoscope, F-5]). The passage involves several shifts of fingering positions. Of course, there are alternate approaches, and you may wish to search for one that works better for you; but this is what I play. (The right hand alternates downstrokes and upstrokes.)