[left that other site]

How does she know the photos were taken against their will? They may have been rewarded for posing, or they may have been proud to be photographed with this new technology.

That is an excellent point. In fact, "candid" photography was nearly impossible back then, as the shutter needed to be open for almost 60 seconds to get a decent exposure. A person had to sit very still for a photograph.

[Williams]

It’s not an excellent point, they were slaves. Do you honestly think they could have opted not to be photographed that day? Not even possible.