Distance is an awesome compressor. Use that to your advantage. Just in case just honestly say that "I have never recorded an opera singer before, can we quickly do a short test record". They rarely say "no", unless they are fucking uptight cunts. I heard Tarja Turunen was recorded with a figure 8 mic because she didn't want to use headphones, so they just aimed the blind spot of the fig8 mic to the speaker that was blasting the music next to her face.
Set up and record several microphones, at several distances and polar patterns:
- omni, cardioid, super cardioid, figure eight, ribbon, dynamic, condenser...
- also try different distances like 30cm away, 50cm away, 1m away, 2m away, 3m away, 5m away etc
But important is that you setup, gain stage and test that they are patched correctly BEFORE the singer arrives. I would aim for around -30dB with further mics and -40dB level with closer mics with your voice since the opera singers will most likely blast you away when it comes to sound pressure. Then record a short clip with all the microphones with the singer and ask the singer to come to the control room to listen to the different microphones and then use the one that sounded the best.
If you have a few different opinions what sounded the best, just record all of those and use the one on the recording that fits the mix the best. When you have made your choice, just remove all the other microphones from the room quickly and get down to business. The teardown should take about 1-5 minutes max; Unplug cable, move the mic aside, done.
