Don't import picamera to build system metadata

openflexure_microscope/microscope.py

@@ -10,7 +10,6 @@ from openflexure_microscope.stage.base import BaseStage
 from openflexure_microscope.stage.mock import MockStage
 from openflexure_microscope.camera.base import BaseCamera
 from openflexure_microscope.camera.mock import MockStreamer
-from openflexure_microscope.camera.pi import PiCameraStreamer
 
 from openflexure_microscope.utilities import serialise_array_b64
 from openflexure_microscope.plugins import PluginLoader
@@ -286,16 +285,16 @@ class Microscope:
         }
 
         # Store an encoded copy of the PiCamera lens shading table, if it exists
-        if self.camera and isinstance(self.camera, PiCameraStreamer):
+        if self.camera and hasattr(self.camera, "read_lens_shading_table"):
             # Read LST. Returns None if no LST is active
             lst_arr = self.camera.read_lens_shading_table()
 
             b64_string, dtype, shape = serialise_array_b64(lst_arr)
-            
+
             system_metadata["lens_shading_table"] = {
                 "b64_string": b64_string,
                 "dtype": dtype,
-                "shape": shape
+                "shape": shape,
             }
-        
-        return system_metadata
+
+        return system_metadata