Working with performers who use sign language presents particular challenges to filming. Although clarity is critical in showing the signer, audiences are pretty sophisticated now, especially those who watch feature films, tv series and ads – they’re used to seeing fast edits and effects. A few decades ago the editing convention was to include all the steps in explaining the action. To get from the car to the apartment the camera had to show the street, the door, the elevator and opening the door. Now, that’s shown in a few frames. So it’s not always desirable to stick to a single front-on shot of a signer. You want to keep the viewer’s attention too.
The trouble is, with a signed performance, as soon as you cut away from the signer, the narrative comes to a dead halt, unless the cutaway shots themselves keep the narrative thread going, so go for that, be much more careful with the cutaway (b-roll) shots and make them very relevant to the story.
You can also change camera angle or viewpoint, but in doing so, the viewer needs to be able to react to this. The signer may have changed size and position in the frame, for example. So you can do that, sure, but give a few beats of time before the signing continues for the viewer to take this in.
Conversation and speech have a natural flow and there are places, usually at the end of a sentence, where it’s natural to cut away from the speaker. The same thing applies to editing footage of a signer, just wait for the end of the idea/thought/sentence. That will look most natural. The hands have reached a rest position and the gaze indicates completion (of that idea or thought). With an audio track, it’s easy to spot the places where speech finishes, and with signing, too, just wait for the natural rest point in the flow.