Addressing the elephant in the room, (has huge ears of-course) it's not really a comparison between dubbing and on-set audio. But, you have to make your own decisions based on what works for you.
The advantages of sync-sound are many, let's talk about them one-by-one.
Advantages:
1. You hear the character - Emotions
Yes, you read that right. Hearing the character with exact emotions. Imagine - the stage is set, all departments are now in the dark and the actors are catching the light. They are in their zone and deliver the dialogues with the exact emotion the director wants. The shot is done and director rejoices! But, there's a problem - the actor needs to carry this emotion later (for 4 months) into a dubbing studio, where he needs to interact with the microphone. Not happening right? This is why it would have been best to record dialogue on location.
2. Boom Microphone - Perspective
The dubbing studio will have a microphone placed near a podium. The shot won't matter, all that matters is the intelligibility of dialogue. While on a film set, the boom operator would give depth to audio. We call it perspective. The closer the shot, the audio would be louder and proximity effect comes in to play. For a mid-shot the audio would not be so loud, and get the surrounding reflections as well. Do keep in mind - a lot of all this depends on the type of location, which is covered in this article.
3. Ambience - Surroundings
While recording the dialogues, there is always an opportunity to record the ambience of our shooting location. This has to be discussed with the sound designer or the post production supervisor prior to finalizing the audio equipment for shoot. The ambience are like roots of the tree. The tree being the scene - it could have any colour of leaves, birds could be sitting on it's branches, fruits of many colours - but, the roots give it the strength to stand. Ambience gives the characters the roots to present themselves.
4. Covid-19 and Sync Sound Recording - Minimize Contact
Since we are going through a pandemic, the best way is to minimise contact with people. Wise decision is to go for sync sound so the actor doesn't have to spend more time inside a studio (ADR will still be needed for noisy locations, actor's preference, clothing issues, etc.) which can be further minimised by recording wild takes (on-set dubbing).
5. Script supervisor's happiness - Monitoring Headphones
The script supervisor needs to listen to dialogues as clearly as possible. This requirement is fulfilled by the sound department on a film set. Even for the wide shots, the dialogue is picked up by lapel microphone. The audio feed is also sent to the camera for a scratch track.
DECISION MAKER VENN DIAGRAM
Preparation:
1. Location Recce - Tech Recce
The Recce is an important part for sync sound recording. During a tech recce, the recordist carries an audio recorder which serves as a reference for particular location. There are major decisions made after a Recce, which include, the kind of equipment needed, number of members in the sound department, and noise suppression material to be carried to the location.
2. Blankets, Mattresses - Noise Isolation
After the Recce, a requirement of Blankets, Mattresses, etc is provided by the sound department to production. This is important for the dialogue to be recorded on certain locations.
3. Sound Lock team - Sync Sound Security
At some locations, the crowd has to managed in an organised fashion without hampering the working of local community. This is a specialised job, and the sync sound security takes care of problems arising out of location disturbances due to community.
4. Crew - Co-Operation
I can't press on this enough - until and unless the crew has internal co-ordination, nothing good can be achieved. The mobile phones ringing between the shots, crew talking during rehearsals (and between takes sometimes), actors not satisfied with the crew, everything adds up to the dialogues we record as the sync sound recordist. The sound department and the crew has to have co-operation to record high quality dialogues on-set.
