This 'lesson' relies heavily on the assumption that other learner guitarists will have run into the same problems as me. This of course might not be true. I'm guessing a bit here. I have on the other hand thought about it logically, and it's seems to be an issue with the way a guitar works rather than with my own particular blind spot for at least 6 of the key signatures. So while writing this, it's probably best if I abandon the all-encompassing group hug of we, and stick with the egotistical I.
As a beginner guitarist, I found myself becoming very familiar with keys such as, C, G, D, A, E and F, but when it came to keys such as, Ab, EB, Db etc., my mind would always take a vacation and leave me counting on my fingers.
So why do I know the key of D but not Db? Why can I reel off the notes of A as unthinkingly as if they were the letters of the alphabet, but with Ab, I have to refer to a mental chart?
I believe there are 2 factors at play here. The first is the design of the guitar, which lends itself to some keys and not others because of the availability of open strings. The second is that the unconscious mind only gives us access to the absolute minimum amount of information needed to perform any task, and keeps the rest locked-up tight.
It has been proven that the unconscious mind not only absorbs everything we experience, but also stores it EVERYTHING! So if you glanced at a chart of key signatures 5 years ago, a hypnotist could refer you back to the time and have you reel it off as confidently as if you had it in front of you. Amazing!
The trouble is that our unconscious minds, as well as having a chart of all 12 key signatures, also know that we're guitar players, and so we only need half of them.
If we're honest, we guitar players are a pretty lazy bunch. If we want to play a song in Ab on an acoustic guitar, we can always slap a capo on the 1st fret, and think in G. If metal/rock guitarists want the more unusual feel of Eb minor, they tune down a half step and think in E minor. And because the shapes on a guitar fretboard are so movable, even in standard tuning with no capo, we can still get away with thinking A while we play in Bb. Can't we? Surely it's not just me who's this lazy. It's the way the mind works. Isn't it?
Okay, I've accepted that no matter how much I study, my mind isn't going to let me familiarise myself with the half of the key signatures that are less used. So here's a trick I came up with.
I can't believe no-one ever mentioned this. I've never read it anywhere. Perhaps it's so obvious that people think it's not worth mentioning. Maybe it's just Captain Stupid here who took 20 years to realise it.
The fact is if you're totally familiar with half of the key signatures, you have the means by which to get access to the other half. It's unbelievably simple.
'Author braces himself to be laughed at for not realising this sooner'.
If you know the key of G contains 1 sharp and it's F, you also know that the key of Gb contains 1 natural and it's also F. Everything else is flat: Gb, Ab, Bb, Cb, Db, Eb, F. If you know the key of D contains 2 sharps and they are F and C, Db contains 2 naturals, and they are F and C, everything else is flat: Db, Eb, F, Gb, Ab, Bb, C. A has 3 sharps, F, C, and G. Ab has 3 naturals, F, C and G: Ab, Bb, C, DB, EB, F, G.
Adversely, if you know that the key of F contains 1 flat and it's B, then F# contains 1 natural, and it's B. Everything else is sharp: F#, G#, A#, B, C#, D#, E#.
It's so obvious! You can stop laughing now.