In most cases, the answer is no. Using a microphone is not necessary. However, yes, it can be a way to improve the quality of your recordings:
Indoors, in a quiet environment, there is no need for a microphone with Kannelle because we anticipate the distance between the interviewee and the camera to ensure good sound quality.
Outdoors or in a noisy environment, and if you want to give the floor to a collaborator (versus simply filming a work environment) yes it is nowadays useful to have a lapel microphone that you will be able to connect to your phone and that will directly overwrite the sound. This way, you will have a better sound without having to deal with separated video track and audio track. If you want suggestions of quality lapel microphones, contact us :)
In the future, we will continue to work on R&D modules allowing you to always improve the sound quality outdoors or in a noisy environment!