diff --git a/camerad/CMakeLists.txt b/camerad/CMakeLists.txt
index aa72d47..681f56f 100644
--- a/camerad/CMakeLists.txt
+++ b/camerad/CMakeLists.txt
@@ -117,13 +117,20 @@ else()
   endif()
 endif()
 
+# ----------------------------------------------------------------------------
+# Separate the registration TU from the instrument implementation so that
+# the registration is compiled into the final target.
+# ----------------------------------------------------------------------------
+set (INSTRUMENT_REGISTRATION ${INSTRUMENT_SOURCES})
+list (FILTER INSTRUMENT_REGISTRATION INCLUDE REGEX "_interface_factory\\.cpp$")
+list (FILTER INSTRUMENT_SOURCES EXCLUDE REGEX "_interface_factory\\.cpp$")
+
 # ----------------------------------------------------------------------------
 # Camera Interface Base
 # ----------------------------------------------------------------------------
 list (APPEND INTERFACE_SOURCES
   ${CAMERAD_DIR}/camera_interface.cpp
   ${CAMERAD_DIR}/image_process.cpp
-  ${INSTRUMENT_SOURCES}
   )
 add_library(${INTERFACE_TARGET} ${INTERFACE_SOURCES})
 target_link_libraries(${INTERFACE_TARGET}
@@ -132,6 +139,18 @@ target_link_libraries(${INTERFACE_TARGET}
                       )
 target_include_directories(${INTERFACE_TARGET} PUBLIC ${INTERFACE_INCLUDES})
 
+# ----------------------------------------------------------------------------
+# instrument implementation, if any.
+# objects shared by the final targets, not depended on as a library
+# ----------------------------------------------------------------------------
+if (INSTRUMENT_SOURCES)
+  add_library(instrument_obj OBJECT ${INSTRUMENT_SOURCES})
+  target_link_libraries(instrument_obj ${INTERFACE_TARGET})
+  set (INSTRUMENT_OBJECTS $<TARGET_OBJECTS:instrument_obj>)
+else()
+  set (INSTRUMENT_OBJECTS "")
+endif()
+
 # ----------------------------------------------------------------------------
 # External libraries, such as FITS, etc.
 # ----------------------------------------------------------------------------
@@ -164,6 +183,8 @@ find_package(Threads)
 add_executable(camerad
   ${CAMERAD_DIR}/camerad.cpp
   ${CAMERAD_DIR}/camera_server.cpp
+  ${INSTRUMENT_REGISTRATION}
+  ${INSTRUMENT_OBJECTS}
   )
 
 # ----------------------------------------------------------------------------
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index 6d4e3a2..eabac89 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -29,6 +29,8 @@ find_package(pybind11 CONFIG REQUIRED)
 
 pybind11_add_module(camera_interface
   ${PROJECT_BASE_DIR}/python/camera_interface_module.cpp
+  ${INSTRUMENT_REGISTRATION}
+  ${INSTRUMENT_OBJECTS}
 )
 
 target_include_directories(camera_interface PRIVATE