One of the main reasons we look at this painting as out of the ordinary is because he was able to capture images the way we take photographs today. Kind of cropped.
He could paint anything, he was not particularly interested in ballet, just the fact where he positioned the people in relation to the whole.
Also, Degas painted the things that were popular in his time. One of those was ballet. As mentioned he painted it behind the scenes as well as during the performances the public saw. He showed the dancers lacing up their shoes, the Ballet master giving orders to the dancers during practice. He was fascinated by the costumes and the dedication of the dancers
