diff --git a/src/ess/amor/resolution.py b/src/ess/amor/resolution.py
index 39e30d2..5c395e9 100644
--- a/src/ess/amor/resolution.py
+++ b/src/ess/amor/resolution.py
@@ -44,11 +44,9 @@ def wavelength_resolution(
         The angular resolution variable, as standard deviation.
     """
     pixel_position = da.coords["position"]
-    distance_between_choppers = (
-        chopper_2_position.fields.z - chopper_1_position.fields.z
-    )
     chopper_midpoint = (chopper_1_position + chopper_2_position) * sc.scalar(0.5)
-    chopper_detector_distance = pixel_position.fields.z - chopper_midpoint.fields.z
+    distance_between_choppers = sc.norm(chopper_2_position - chopper_1_position)
+    chopper_detector_distance = sc.norm(pixel_position - chopper_midpoint)
     return WavelengthResolution(
         fwhm_to_std(distance_between_choppers / chopper_detector_distance)
     )
@@ -77,7 +75,11 @@ def sample_size_resolution(
     """
     return fwhm_to_std(
         sc.to_unit(sample_size, "m")
-        / sc.to_unit(da.coords["position"].fields.z, "m", copy=False)
+        / sc.to_unit(
+            sc.norm(da.coords["position"] - da.coords["sample_position"]),
+            "m",
+            copy=False,
+        )
     )
 
 
@@ -109,7 +111,11 @@ def angular_resolution(
             sc.to_unit(
                 sc.atan(
                     sc.to_unit(detector_spatial_resolution, "m")
-                    / sc.to_unit(da.coords["position"].fields.z, "m", copy=False)
+                    / sc.to_unit(
+                        sc.norm(da.coords["position"] - da.coords["sample_position"]),
+                        "m",
+                        copy=False,
+                    )
                 ),
                 theta.bins.unit,
                 copy=False,