diff --git a/tofu/data/_class09_GeometryMatrix.py b/tofu/data/_class09_GeometryMatrix.py
index 670e72f8b..534cff910 100644
--- a/tofu/data/_class09_GeometryMatrix.py
+++ b/tofu/data/_class09_GeometryMatrix.py
@@ -97,12 +97,14 @@ def add_geometry_matrix(
     def get_geometry_matrix_concatenated(
         self,
         key=None,
+        key_cam=None,
     ):
         """ Assemble the geometry matrix """
 
         return _compute._concatenate(
             coll=self,
             key=key,
+            key_cam=key_cam,
         )
 
     # -----------------
@@ -147,4 +149,4 @@ def plot_geometry_matrix(
             fs=fs,
             dcolorbar=dcolorbar,
             dleg=dleg,
-        )
+        )
\ No newline at end of file
diff --git a/tofu/data/_class10_checks.py b/tofu/data/_class10_checks.py
index 15285d5d3..e2c00ff13 100644
--- a/tofu/data/_class10_checks.py
+++ b/tofu/data/_class10_checks.py
@@ -73,7 +73,7 @@ def _compute_check(
     )
 
     key_diag = coll.dobj['geom matrix'][key_matrix]['diagnostic']
-    # key_cam = coll.dobj['geom matrix'][key_matrix]['camera']
+    key_cam = coll.dobj['geom matrix'][key_matrix]['camera']
 
     keybs = coll.dobj['geom matrix'][key_matrix]['bsplines']
     deg = coll.dobj['bsplines'][keybs]['deg']
@@ -82,7 +82,10 @@ def _compute_check(
     mtype = coll.dobj[coll._which_mesh][keym]['type']
 
     # matrix itself
-    matrix, ref, dind = coll.get_geometry_matrix_concatenated(key_matrix)
+    matrix, ref, dind = coll.get_geometry_matrix_concatenated(
+        key_matrix,
+        key_cam=key_cam,
+    )
     lkmat = coll.dobj['geom matrix'][key_matrix]['data']
     units_gmat = coll.ddata[lkmat[0]]['units']
     nchan, nbs = matrix.shape[-2:]
@@ -98,6 +101,7 @@ def _compute_check(
         coll=coll,
         key_diag=key_diag,
         key_data=key_data,
+        key_cam=key_cam,
     )
 
     # sigma
@@ -479,12 +483,14 @@ def _check_data(
     coll=None,
     key_diag=None,
     key_data=None,
+    key_cam=None,
 ):
 
     # load ddata from key_data
     ddata = coll.get_diagnostic_data_concatenated(
         key=key_diag,
         key_data=key_data,
+        key_cam=key_cam,
         flat=True,
     )
 
@@ -501,6 +507,7 @@ def _check_sigma(
     coll=None,
     key_diag=None,
     key_sigma=None,
+    key_cam=None,
     sigma=None,
     ddata=None,
     nchan=None,
@@ -537,6 +544,7 @@ def _check_sigma(
             coll=coll,
             key=key_diag,
             key_data=key_sigma,
+            key_cam=key_cam,
             flat=True,
         )
 
diff --git a/tofu/data/_class9_compute.py b/tofu/data/_class9_compute.py
index 8e46433b4..3493a4e47 100644
--- a/tofu/data/_class9_compute.py
+++ b/tofu/data/_class9_compute.py
@@ -479,6 +479,7 @@ def _store(
 def _concatenate(
     coll=None,
     key=None,
+    key_cam=None,
 ):
 
     # ------------
@@ -491,11 +492,19 @@ def _concatenate(
         allowed=lok,
     )
 
+    key_cam0 = coll.dobj['geom matrix'][key]['camera']
+    key_cam = ds._generic_check._check_var_iter(
+        key_cam, 'key_cam',
+        default=key_cam0,
+        types=(list, tuple),
+        types_iter=str,
+        allowed=key_cam0,
+    )
+
     # -----------
     # concatenate
 
     key_data = coll.dobj['geom matrix'][key]['data']
-    key_cam = coll.dobj['geom matrix'][key]['camera']
     axis = coll.dobj['geom matrix'][key]['axis_chan']
 
     ref = list(coll.ddata[key_data[0]]['ref'])