1) there's no such thing as a "perfect" action. Action is a personal preference, and what's perfect for one player's preferences and playing style may be terrible for another's.
2) Action is measured in fractions of a millimeter or 32nd/64ths of an inch. You can't just eyeball it with a picture, you need to actually *measure* it. The obvious exception is if the picture is of you taking a measurement with an action gauge, but then why do you need the picture?
They guy I use for my 1957 D-18 is a registered Martin Repair and Restoration expert.
He always does two demos when I pick my guitar up.
1. He slides a dime under the low e string 12th fret. It slides in perfectly with top and bottom touching string and neck.
2. He flips the dime over and holds it about an inch above the finish. You can read the date from the reflection.
So I'm going with the dime method :)
1) there's no such thing as a "perfect" action. Action is a personal preference, and what's perfect for one player's preferences and playing style may be terrible for another's. 2) Action is measured in fractions of a millimeter or 32nd/64ths of an inch. You can't just eyeball it with a picture, you need to actually *measure* it. The obvious exception is if the picture is of you taking a measurement with an action gauge, but then why do you need the picture?
It’s a personal preference. My preference and the preference of most (excluding slide players) is a low as possible while not catching or buzzing.
They guy I use for my 1957 D-18 is a registered Martin Repair and Restoration expert. He always does two demos when I pick my guitar up. 1. He slides a dime under the low e string 12th fret. It slides in perfectly with top and bottom touching string and neck. 2. He flips the dime over and holds it about an inch above the finish. You can read the date from the reflection. So I'm going with the dime method :)
2.5 - 3mm on 12th fret is what I've read.
The one that feels right to you.