"What app do you use?"
When I started my channel, I took photographs on my phone, which is a Moto G4 Plus. I used the normal camera app that came with the phone. After taking the photographs, I transferred them to my laptop and imported them into Adobe Premier Pro CS3, where I rendered the photographs into video clips at 12 frames per second. I create one short video clip for each shot. I then used these to create the final video, adding voices, effects, titles, sound effects and music as required.
Since September 2018, I've been using a Canon EOS 1200D instead of my phone. This is a DSLR camera, and allows for greater control over exposure, focus and depth of field. After taking the photographs, however, I am following the same process as before.
I vary my frame rate depending on what I am shooting, but I use 12 fps as my standard rate. I will consider increasing to 15fps or (more likely) 24 fps to see whether it improves my animations.