It used to be that a cinematographer needed a ton of filters in their kit to create the images they needed.
I remember our cine teacher in graduate school rolling up with a packed SUV where his entire payload was just case after case of filters, all with his name engraved on them. It was how you crafted your image.
With the digital revolution, we have a lot more power in post, and while it's still great to get physical glass in front of the lens if you possibly can, you can do a lot of what filters used to do in post if you can't spend thousands building your filter kit.
There is still one set of filters you absolutely need on set and just can't recreate in post. Neutral density filters, or ND filters, are ones you still want in a filter tray. Especially infrared control (IR) ND filters.
