diff --git a/openflexure_microscope/camera/pi.py b/openflexure_microscope/camera/pi.py
index 4b2a15bf..13f26cd5 100644
--- a/openflexure_microscope/camera/pi.py
+++ b/openflexure_microscope/camera/pi.py
@@ -565,15 +565,20 @@ class PiCameraStreamer(BaseCamera):
         # While the iterator is not closed
         try:
             while True:
-                # reset stream for next frame
+                # Reset the stream for the next frame
                 self.stream.seek(0)
                 self.stream.truncate()
-                # to stream, read the new frame
+                # Sleep for the approximate camera framerate
                 time.sleep(1 / self.camera.framerate * 0.1)
-                # yield the result to be read
+                # Get the latest frame data from the stream
                 frame = self.stream.getvalue()
 
-                # ensure the size of package is right
+                # This loop iterates faster than the PiCamera will collect
+                # frames. On iterations between frames, the buffer will be
+                # empty (because we truncated it earlier). In these cases
+                # we just pass and loop again until a frame is actually present.
+                # This also means that the size of FrameStream is always 1 frame,
+                # since we truncate it here before a new frame can be appended.
                 if len(frame) == 0:
                     pass
                 else: