The square format is intriguing because it circumvents the 'rules' of composition that we are accustomed to using within the 35mm frame. The rule-of-thirds becomes more or less irrelevant – compositions with the subject placed in the centre or close to one of the edges are just as effective.
The square is a very stable shape. The eye doesn't follow the longer edge of the rectangle from side to side (or up and down in the portrait format). Instead it goes around the frame in a circle.
When it comes to composing within the square frame, rather than the rule-of-thirds I prefer to concentrate on what I call the 'four S's of composition': simplicity, subtlety, shape and space. They are all valid elements of composition, regardless of what aspect ratio you are working in, but they seem to become stronger in the square format.
- Andrew S. Gibson -