the Victorian Child Cult saw child-nudity as being about innocence. Photographs of nude children were actually mainstream and fashionable in Carroll's time and most photographers, including Oscar Rejlander and Julia Margaret Cameron photographed nude children as a matter of course. Child nudes even appeared on Victorian Christmas cards. It's the fact that Carroll's biographers were unaware of this and looked at his nude child studies through modern eyes that has helped seal the impression he was a pedophile.
External links:
Julia Margaret Cameron
Charles Dodgson and the Victorian Cult of the Child