When working on set of a large production crews, vanities, and clients are used to having multiple monitors to see what the camera sees. Typically you'll have a larger monitor for video village, an assistant’s monitor mounted to or near the camera, an external viewfinder (EVF) for the camera operator. But when shooting in the field or in studios with DSLR’s, you have to choose one of those.
You can only see a camera image in either 1) the camera’s built-in LCD or 2) through the camera’s HDMI output. It won’t send a video signal for two things at the same time. If you don't prepare for this, it can really disrupt your workflow.
But don't freak out — everything is manageable… You could use the video village monitor during setups so that the director, producer or client can see what’s up - but unplug it when it comes time to shoot and operate with the camera’s LCD. You can then plug the monitor back in and watch playback at video village if the director or others need it.
Other options, you can get a cross converter - these receive an HDMI signal and output two HD–SDI signals. This way you can run a BNC cable to video village and another to an EVF. Yes… a cross converter will cost you, so you will have to weigh the costs vs. the benefits if you've got a limited budget.
Be sure to check back next Tuesday for a lesson on packing equipment in a way that’s convenient, accessible, and mobile.