Actually, I answered my own question. So for anyone else interested, here is a link to the New York City Transit Rules Page. And this is the rule regarding photography.
3. Photography, filming or video recording in any facility or conveyance is permitted except that ancillary equipment such as lights, reflectors or tripods may not be used. Members of the press holding valid identification issued by the New York City Police Department are hereby authorized to use necessary ancillary equipment. All photographic activity must be conducted in accordance with the provisions of this Part.
Also to bear in mind as to conduct . . .
Section 1050.7 states riders may not . . .
9. Conduct himself or herself in any manner which may cause or tend to cause annoyance, alarm or inconvenience to a reasonable person or create a breach of the peace.
(And how many times do get on people's cases for not Googling first. Yeah, smacking my forehead repeatedly here.)