Capos are an essential tool for the Bluegrass guitarist. A capo lets you play a song in an unfamiliar key. It is especially useful in Bluegrass where the sound of open strings and chords are preferred.
Using a capo is fairly straightforward, as illustrated in the following table. For example, to play in the key of C#, you could put the capo on the first fret and play as though you were in the key of C. To play in the key of Bb, put the capo on the third fret and play as though you were in the key of G. Please notice that there are multiple options for any key.
|Capo Transposition Table|
|1st Fret||C# or Db||D# or Eb||F||F# or Gb||G# or Ab||A# or Bb||C|
|2nd Fret||D||E||F# or Gb||G||A||B||C# or Db|
|3rd Fret||D# or Eb||F||G||G# or Ab||A# or Bb||C||D|
|4th Fret||E||F# or Gb||G# or Ab||A||B||C# or Db||D# or Eb|
|5th Fret||F||G||A||A# or Bb||C||D||E|
There are numerous designs for capos, and some are definitely better than others. The best designs are those that let you adjust the force exerted on the neck. You only want enough force applied so that the open notes on each string sound clean. Too little force, and the strings buzz. Too much force can also cause distortion - or worse, dent your guitar's neck.
One of the most popular enduring designs is the "U-shape" capo. Examples are the Elliott and Paige capos. Another design that has stood the test of time is the Shubb capo, which attaches from the side of the neck. The Victor and the G7th capos are also designs where the capo is attached from the side.
If you want to learn more about capos, check out the Sterner Capo Museum. It offers photos, and historical notes and much more.