What is the sensitivity of the film we usually use for photography? Is the higher the sensitivity, the more expensive?

Ordinary 200 will do.

But the size is up to you.

The lower the sensitivity, the slower the shutter speed.

The higher the sensitivity, the faster the speed, which is more suitable for shooting in dark light or high-speed motion.

Everything has advantages and disadvantages,

The film with low sensitivity has fine particles and relatively clear images.

The film with high sensitivity has coarse grains and relatively coarse images.

Choose a movie according to your idea.

This camera has something to do with it.