Here is a great question I saw this morning on a professional film composer FB group. It is from someone else - not me. Since I have not yet had the honor of working with a live orchestra for any of my films, the issue has not yet come up for me. This question had about 25 responses last time I looked. There seemed to be a consensus but I will not mention that any further so people here can discuss the issue and think about it without 'pre-disposition'. For those of us who a fortunate enough to score a film for a live orchestra and plan on adding pitched electronic sounds, tuning could be an 'issue'. From what I have heard so far from professional composers and classical musicians, 442 tuning is common in Europe whereas in the US it is mostly 440:
"Seeking advice on orchestral recording: I'm about to record a film's soundtrack with a classical ensemble that tune their instruments in 442 hz. However, my sampled mock-up tracks are in 440 hz, and I'm intending to use them to reinforce the sound (along with other VSTs and synths)
Should I re-tune my samples to 442 hz or ask the orchestra to play at 440 hz, even when that would mean that they wont be completely comfortable with it?