diff --git a/openflexure_microscope/api/app.py b/openflexure_microscope/api/app.py
index b1f83a20..61112ad0 100644
--- a/openflexure_microscope/api/app.py
+++ b/openflexure_microscope/api/app.py
@@ -3,13 +3,20 @@ from gevent import monkey
 
 monkey.patch_all()
 
+import sys
 import time
 import atexit
 import logging, logging.handlers
 
+# Look for debug flag
+if "-d" in sys.argv or "--debug" in sys.argv:
+    log_level = logging.DEBUG
+else:
+    log_level = logging.INFO
+
 # Set root logger level
 logger = logging.getLogger()
-logger.setLevel(logging.INFO)
+logger.setLevel(log_level)
 
 import os
 import pkg_resources
diff --git a/openflexure_microscope/camera/mock.py b/openflexure_microscope/camera/mock.py
index 9dc727c4..ec61bc7e 100644
--- a/openflexure_microscope/camera/mock.py
+++ b/openflexure_microscope/camera/mock.py
@@ -197,19 +197,14 @@ class MissingCamera(BaseCamera):
             bayer (bool): Store raw bayer data in capture
         """
 
-        if isinstance(output, CaptureObject):
-            target = output.file
-        else:
-            target = output
-
         with self.lock:
-            if isinstance(target, str):
-                target = open(target, "wb")
+            if isinstance(output, str):
+                output = open(output, "wb")
 
-            target.write(self.stream.getvalue())
+            output.write(self.stream.getvalue())
 
-            if isinstance(target, str):
-                target.close()
+            if isinstance(output, str):
+                output.close()
 
     # HANDLE STREAM FRAMES
 
diff --git a/openflexure_microscope/camera/pi.py b/openflexure_microscope/camera/pi.py
index a73ea5d1..b9cdfbd5 100644
--- a/openflexure_microscope/camera/pi.py
+++ b/openflexure_microscope/camera/pi.py
@@ -115,11 +115,6 @@ class PiCameraStreamer(BaseCamera):
             "picamera_lst.npy"
         )  #: str: Path of .npy lens shading table file
 
-        # Create an empty stream
-        self.stream = io.BytesIO()
-
-        # Start streaming
-        self.start_worker()
 
     @property
     def configuration(self):
@@ -520,12 +515,6 @@ class PiCameraStreamer(BaseCamera):
         Returns:
             output_object (str/BytesIO): Target object.
         """
-
-        if isinstance(output, CaptureObject):
-            target = output.file
-        else:
-            target = output
-
         with self.lock:
             logging.info("Capturing to {}".format(output))
 
@@ -535,20 +524,20 @@ class PiCameraStreamer(BaseCamera):
                 time.sleep(0.1)
 
             self.camera.capture(
-                target,
+                output,
                 format=fmt,
                 quality=100,
                 resize=resize,
                 bayer=(not use_video_port) and bayer,
                 use_video_port=use_video_port,
             )
-            time.sleep(0.1)
+            #time.sleep(0.1)
 
             # Set resolution and start stream recording if necessary
             if not use_video_port:
                 self.start_stream_recording()
 
-            return target
+            return output
 
     def yuv(
         self, use_video_port: bool = True, resize: Tuple[int, int] = None
diff --git a/openflexure_microscope/captures/capture.py b/openflexure_microscope/captures/capture.py
index 70bee3ec..6ce0f42a 100644
--- a/openflexure_microscope/captures/capture.py
+++ b/openflexure_microscope/captures/capture.py
@@ -10,6 +10,9 @@ from PIL import Image
 import dateutil.parser
 import atexit
 
+from gevent.fileobject import FileObjectThread
+import gevent
+
 from collections import OrderedDict
 
 from openflexure_microscope.camera import piexif
@@ -118,12 +121,19 @@ def capture_from_exif(path, exif_dict):
 
 class CaptureObject(object):
     """
-    StreamObject used to store and process on-disk capture data, and metadata.
+    File-like object used to store and process on-disk capture data, and metadata.
     Serves to simplify modifying properties of on-disk capture data.
     """
 
     def __init__(self, filepath) -> None:
         """Create a new StreamObject, to manage capture data."""
+        # Stream for buffering capture data
+        self.stream = io.BytesIO()
+        # Event to notify when the stream has finished writing to disk
+        #self.file_ready = Event()
+        self.file_ready = gevent.event.Event()
+        # Lock to control disk file access
+        self.file_lock = gevent.lock.BoundedSemaphore()
 
         # Store a nice ID
         self.id = uuid.uuid4()  #: str: Unique capture ID
@@ -148,6 +158,25 @@ class CaptureObject(object):
         # Thumbnail (populated only for PIL captures)
         self.thumb_bytes = None
 
+    def write(self, s):
+        self.stream.write(s)
+        gevent.sleep()
+
+    def _stream_to_file(self):
+        logging.info(f"Writing to disk {self.file}")
+        with FileObjectThread(open(self.file, "wb"), 'wb')  as outfile, self.file_lock:
+            outfile.write(self.stream.getbuffer())
+        self.stream.close()
+        self.file_ready.set()
+        logging.info(f"Finished writing to disk {self.file}")
+        gevent.sleep()
+
+    def flush(self):
+        logging.debug(f"Flushing {self.file}")
+        gevent.spawn(self._stream_to_file)
+        gevent.sleep()
+        logging.debug(f"Returning flushing {self.file}")
+
     def open(self, mode):
         return open(self.file, mode)
 
@@ -221,24 +250,30 @@ class CaptureObject(object):
         self.save_metadata()
 
     def save_metadata(self) -> None:
+        #gevent.get_hub().threadpool.spawn(self.synchronous_save_metadata)
+        gevent.spawn(self.synchronous_save_metadata)
+        gevent.sleep()
+
+    def synchronous_save_metadata(self) -> None:
         """
         Save metadata to exif, if supported
         """
         global EXIF_FORMATS
 
         if self.format.upper() in EXIF_FORMATS and self.exists:
-            logging.debug("Writing exif data to capture file")
-            # Extract current Exif data
-            exif_dict = piexif.load(self.file)
-            # Serialize metadata
-            metadata_string = json.dumps(self.metadata, cls=JSONEncoder)
-            logging.debug(f"Saving metadata string to file: {metadata_string}")
-            # Insert metadata into exif_dict
-            exif_dict["Exif"][piexif.ExifIFD.UserComment] = metadata_string.encode()
-            # Convert new exif dict to exif bytes
-            exif_bytes = piexif.dump(exif_dict)
-            # Insert exif into file
-            piexif.insert(exif_bytes, self.file)
+            with self.file_lock:
+                logging.debug("Writing exif data to capture file")
+                # Extract current Exif data
+                exif_dict = piexif.load(self.file)
+                # Serialize metadata
+                metadata_string = json.dumps(self.metadata, cls=JSONEncoder)
+                logging.debug(f"Saving metadata string to file: {metadata_string}")
+                # Insert metadata into exif_dict
+                exif_dict["Exif"][piexif.ExifIFD.UserComment] = metadata_string.encode()
+                # Convert new exif dict to exif bytes
+                exif_bytes = piexif.dump(exif_dict)
+                # Insert exif into file
+                piexif.insert(exif_bytes, self.file)
 
     @property
     def metadata(self) -> dict:
@@ -286,7 +321,7 @@ class CaptureObject(object):
 
         if self.exists:  # If data file exists
             logging.info("Opening from file {}".format(self.file))
-            with open(self.file, "rb") as f:
+            with open(self.file, "rb") as f, self.file_lock:
                 d = io.BytesIO(f.read())  # Load bytes from file
             d.seek(0)  # Rewind loaded bytestream
             # Create a copy of the bytestream bytes
diff --git a/openflexure_microscope/microscope.py b/openflexure_microscope/microscope.py
index c1fe348d..7301ec73 100644
--- a/openflexure_microscope/microscope.py
+++ b/openflexure_microscope/microscope.py
@@ -7,6 +7,8 @@ import pkg_resources
 import uuid
 from typing import Tuple
 
+import gevent
+
 from openflexure_microscope.captures import CaptureManager
 
 from openflexure_microscope.stage.mock import MissingStage
@@ -299,6 +301,7 @@ class Microscope:
         tags: list = None,
         metadata: dict = None,
     ):
+        logging.debug(f"Microscope capturing to {filename}")
         if not annotations:
             annotations = {}
         if not metadata:
@@ -313,14 +316,22 @@ class Microscope:
             )
 
             # Capture to output object
+            logging.info("Starting microscope capture...")
             self.camera.capture(
-                output.file,
+                output,
                 use_video_port=use_video_port,
                 resize=resize,
                 bayer=bayer,
                 fmt=fmt,
             )
+            logging.info("Finished microscope capture...")
 
+
+        def inject_metadata():
+            logging.debug(f"Waiting for {output.file}")
+            # Wait for the file to be written to disk
+            output.file_ready.wait()
+            logging.info(f"Asynchronously injecting EXIF data into {output.file}")
             # Inject system metadata
             output.put_metadata({"instrument": self.metadata})
             # Insert custom metadata
@@ -329,5 +340,10 @@ class Microscope:
             output.put_annotations(annotations)
             # Insert custom tags
             output.put_tags(tags)
+            logging.info(f"Finished injecting EXIF data into {output.file}")
+
+        gevent.spawn(inject_metadata)
+
+        logging.debug(f"Finished capture to {output.file}")
 
         return output
diff --git a/openflexure_microscope/stage/sanga.py b/openflexure_microscope/stage/sanga.py
index 5fa147ae..491d2a6f 100644
--- a/openflexure_microscope/stage/sanga.py
+++ b/openflexure_microscope/stage/sanga.py
@@ -108,6 +108,7 @@ class SangaStage(BaseStage):
         backlash: (default: True) whether to correct for backlash.
         """
         with self.lock:
+            logging.info(f"Moving sangaboard by {displacement}")
             if not backlash or self.backlash is None:
                 return self.board.move_rel(displacement, axis=axis)
 
@@ -145,6 +146,7 @@ class SangaStage(BaseStage):
         """Make an absolute move to a position
         """
         with self.lock:
+            logging.info(f"Moving sangaboard to {final}")
             self.board.move_abs(final, **kwargs)
 
     def zero_position(self):
diff --git a/openflexure_microscope/utilities.py b/openflexure_microscope/utilities.py
index 185478f6..f166ce79 100644
--- a/openflexure_microscope/utilities.py
+++ b/openflexure_microscope/utilities.py
@@ -8,6 +8,7 @@ import logging
 from collections import abc
 from functools import reduce
 from contextlib import contextmanager
+import gevent
 
 
 def deserialise_array_b64(b64_string, dtype, shape):
diff --git a/tests/test_camera.py b/tests/test_camera.py
index 6ed5d44e..6369a651 100644
--- a/tests/test_camera.py
+++ b/tests/test_camera.py
@@ -31,7 +31,7 @@ class TestCaptureMethods(unittest.TestCase):
                 with camera.new_image() as output:
 
                     camera.capture(
-                        output.file, use_video_port=use_video_port, resize=resize
+                        output, use_video_port=use_video_port, resize=resize
                     )
 
                     # Ensure file deletion fails and returns False