Time to get practical, with two sets of real live diminished scale-tone practice patterns (STPPs).
The patterns are in triplets - three notes per beat. The triplets either run up or down, or they skip up-down or down-up.
The diminished chord tones are marked with a little arrow above the music. All the patterns are in C diminished.
Don't try to read from the thumbnail - download the lesson PDF.
Here is the video for the first set. It's at performance speed - something to aim for - so you MUST understand the pattern - "the triplets either run up or down, or they skip up-down or down-up" - and play that.
The fingering must 'sort itself out'. The patterns don't go far, up or down, so you've plenty of time bluff your way through!
The patterns in the second set are in straight semiquavers.
Here is the performance video. Listen, and pin down the patterns, one at a time.
Diminished scales don't actually have a key. They are symmetrical, without a 'home' centre. This makes playing them an excellent opportunity to appreciate pure melodic shape.
Scale Practice Patterns (SPPs)
Scale-tone practice patterns (STPPs)
The MusicartaA methodical approach to keyboard syncopation for