Charlie Dodgson (aka Lewis Carroll) was one of those early photogs. His pictures are very disturbing to the modern eye.
Clearly, the Victorians were completely out of their minds.
It was during Dodson's lifetime that a psychologist convinced the Victorians that the practice was wrong. Laws were passed, and many prominent English photographers destroyed prints and negatives.
Dodson's were destroyed on his death, of thousands, few remain.
Before that it was quite common for a family to pay for professional shots of their kids in the nude, some, as you said, in quite skeevy poses.
Is this movie an outlier, or is it a sign that we are moving back to Victorian standards of what (now is called) child porn?