Question about guitar capos?!

Question about guitar capos?

If i get one, will it lower or raise the pitch of my guitar when i use it, what exactly does it do? I've been playing some songs that require me to tune my guitar a step down, if i get a capo can i do this automatically?

Your question is in 3 parts:

Q. “If I get (a capo), will it lower or raise the pitch of my guitar when I use it?”
A. Using a capo raises the pitch of all strings simultaneously and proportionately. Here’s how: Suppose you are using standard tuning (E-A-D-G-B-E). If you position the capo properly in the 1st fret, your open strings are now all pitched exactly one ½ step higher. Your tuning is now (F-Gb-Eb-Ab-C-F).

Q. “What exactly does it do?”
A. By mathematical design, the string-length from the “nut” to the “bridge” of a stringed instrument (guitar, banjo, mandolin) is a standard length. Using the capo decreases that distance by however many fretlengths you choose. The most valuable use of a capo for me is as a composer/singer. Let’s say I’m writing a song in the key of D and I’m building a chord chart as I go. I may spend a few hours working on the words and the melody for every section of the song, and the entire time I’m using chords in the family of the D key. Then, later on, I go back to play that song for a fellow musician and his response is that I’m being a little timid on my delivery, and that I should consider keying the song up. Good idea. Now, I can either sit down and transpose the entire song from D to Eb (½-step up) or E (full step up) OR…I can clamp the capo on the first or second fret and play the song using the exact same chords I’ve charted in the key of D. The capo does all the work of shifting the fretboard math incrementally upward for me. It’s just a shortcut for transposing, but I like shortcuts when I’m working with other musicians. There are lots of other uses for performance, collaboration, composing, etc., but this is what I use a capo for, primarily.

Q. “I've been playing some songs that require me to tune my guitar a step down. If I get a capo can I do this automatically?”
A. It doesn’t work that way. Because you will decrease the string length no matter where you position the capo, your pitch will only increase. There is no such device that will automatically decrease the pitch of your strings. However, I know a player who likes to keep his acoustic guitar in D-tune (D-G-C-F-A-D) but he leaves his capo on the 2nd fret about 90% of the time. This allows him to play and sing the songs he’s composed in the key of E (the “pocket” for his vocal range), but to quickly step down to the key of D (for a few songs that work better in a slightly lower key) simply by removing the capo.