I'm currently working on cutting together a documentary filmed on a Canon EOS C100. There are few shots that I want to zoom in on using FInal Cut Pro. I'm wondering if anyone knows if there is a limit to how far I can zoom in artificially while still maintaining the image quality needed to display clearly on a large format screen? Is this just going to be a case of my having to trial and error and see for myself? Thanks for any help!
Trial and error is usually the best. I would guess around 120-125% you'll start see a distinct softening of the image. It largely depends on your quality standards as what's an acceptable loss visually. Some people won't got past 110%...so it's very subjective.
If possible I'd run some tests and project on the screen you anticipate showing it on. That may give you the best idea of how it looks.