As far as recording is concerned - no problem as long as you ask first, though it does depend on the circumstances.
Photographs - also depends on the circumstances.
In the early days of the Willie Clancy Summer School we were attending the main concert and had got a seat in the front row (had no intention of recording).
The stage had been set up with the p.a mikes and those of the organisers, who recorded all the events for archiving, when in swept a very well-known English record producer. He re-sited all the existing mikes and placed his own centre-stage.
Everybody was far too polite to mention his behaviour until the fiddle player Sean Maguire, one of the guests, spotted him, jumped off the stage, walked over to your man and said; "My agent's name is *****, my recording fee is ******, and if I see your fingers anywhere near those buttons I'll f*****g dance on them.
As a footnote (no pun intended), the recordist issued a number of albums using similar techniques in different places.
Jim Carroll