Let’s start with the why though. Essentially, third-party EVF offers you consistency across any camera no matter how good or bad the built-in EVF is. If you use a product like the Zacuto EVF, you always know exactly what you’re seeing in the EVF is consistent. You can trust that the colors are what you think they are. It’s good to know that the scopes and focus assist are accurate. Some cameras don’t allow you to install custom LUTS, which is another very handy feature that the Zacuto EVFs have.