diff --git a/src/openflexure_microscope_server/things/camera/picamera.py b/src/openflexure_microscope_server/things/camera/picamera.py
index 40ad6bda..29afc35b 100644
--- a/src/openflexure_microscope_server/things/camera/picamera.py
+++ b/src/openflexure_microscope_server/things/camera/picamera.py
@@ -640,7 +640,8 @@ class StreamingPiCamera2(BaseCamera):
         :param target_white_level: Raw target white level, this should be an integer
             within the range set by the bit-depth of the camera sensor (10-bit for
             PiCamera v2, 12 Bit for Picamera HQ. If None the default will be used for
-            the current sensor. This is approximately 70% saturated.
+            the current sensor. This is approximately 40% saturated, but after gamma
+            curve is applied, the pixel values will have a value around 200.
         :param percentile: The percentile to use instead of maximum. Default 99.9. When
             calculating the brightest pixel, a percentile is used rather than the
             maximum in order to be robust to a small number of noisy/bright pixels.
diff --git a/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py b/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py
index 77175f11..0a5637ab 100644
--- a/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py
+++ b/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py
@@ -120,10 +120,11 @@ def adjust_shutter_and_gain_from_raw(
     :param camera: A Picamera2 object.
     :param target_white_level: The raw value we aim for, the raw value of the brightest
         pixels should be approximately this bright. The value to set depends on the
-        sensor bit depth. We recommend values of 700 for 10-bit sensors and 2800 for
-        12-bit sensors. This is about 70% of saturated once the blacklevel is
+        sensor bit depth. We recommend values of 400 for 10-bit sensors and 1600 for
+        12-bit sensors. This is about 40% of saturated once the blacklevel is
         subtracted. The maximum possible value depends on the sensor bit depth, the
-        sensor blacklevel and the tolerance argument.
+        sensor blacklevel and the tolerance argument. While this only uses 40% of the
+        sensor range, after gamma this corresponds to pixel value ~200.
     :param max_iterations: We will terminate once we perform this many iterations,
         whether or not we converge.  More than 10 shouldn't happen.
     :param tolerance: How close to the target value we consider "done".  Expressed as a