Is it illegal to take pictures without negatives?

Not illegal. Generally, when you go to a photo studio to take photos, you will sign a bill with specific packaging contents (number of negatives, number of fine photos, photo albums, photo frames, etc.). ). This belongs to the agreed content, and what is beyond the scope does not belong to you. To put it simply, if you have agreed with the studio to give as many negatives as possible, then give as many as possible. If there is no agreement, the negative does not belong to you, but actually belongs to the photographer who took your picture.