Originally Posted by: axemaster911The Ionian G major scale, G-A-B-C-D-E-F#-G you referred to is in perfict diatonic scale. w-w-h-w-w-w-h
If the Ionian G major would have been writen =G-A-B-C-D-E-F
w-w-h-w-w-h-w
Then I belive that would show the Ionian G major diatonic scale to be writen with an accidental, or mutated into the Mixolydian.

What I am really saying is dont belive that the diatonic scale in any form has an accidental unless a composer writes it with a note outside the set diatonic pattern regardless of sharps, flats, or naturals.
If I am wrong I am looking forward to examples to prove otherwise.

A diatonic scale isn't a specific scale. A scale is a selection of notes within an octave. You take C Major.
You've got C D E F G A B C with W W H W W W H as your interval structure.

If you take that exact same interval structure and move it to G you have
G A B C D E F# G.

Now, if you take the notes in G Major and start on B you have
B C D E F# G A B with an interval structure of H W W W H W W.

Now, if you pull a bunch of intervals out of your ass and you get
B C Db Eb F G A B you have H H W W W W W.

Those are all examples of a diatonic scale. Notice the similarity between them? They all have 2 half steps regardless of the location and 5 whole steps also regardless of the location. That's what a diatonic scale is. Any scale that meets that criteria. It doesn't matter how many accidentals or what kind of accidental. Accidentals are completely unrelated to what makes a scale diatonic.