weightpounder13:
Intimacy with the lens in the case of the single model is intimacy with the viewer, but with two or more models working together to creat a senual storyline, they should only be focused on each other. In these cases, when one or more of them look deeply into the lens, it breaks the spell.
essentialv:
You are correct that the dynamic changes with more than one model. I would observe, however, that even when only one woman is in the shot, she doesn't necessarily have to be looking directly at the lens.