diff --git a/diffsims/generators/diffraction_generator.py b/diffsims/generators/diffraction_generator.py
index e481526a..27addaa9 100644
--- a/diffsims/generators/diffraction_generator.py
+++ b/diffsims/generators/diffraction_generator.py
@@ -289,16 +289,15 @@ def calculate_ed_data(
         r_spot = np.sqrt(np.sum(np.square(cartesian_coordinates[:, :2]), axis=1))
         z_spot = cartesian_coordinates[:, 2]
 
-        if self.precession_angle > 0:
-            if not self.approximate_precession:
-                # We find the average excitation error - this step can be
-                # quite expensive
-                excitation_error = _average_excitation_error_precession(
-                        z_spot,
-                        r_spot,
-                        wavelength,
-                        self.precession_angle,
-                        )
+        if self.precession_angle > 0 and not self.approximate_precession:
+            # We find the average excitation error - this step can be
+            # quite expensive
+            excitation_error = _average_excitation_error_precession(
+                    z_spot,
+                    r_spot,
+                    wavelength,
+                    self.precession_angle,
+                    )
         else:
             z_sphere = -np.sqrt(r_sphere ** 2 - r_spot ** 2) + r_sphere
             excitation_error = z_sphere - z_spot
@@ -317,7 +316,7 @@ def calculate_ed_data(
                     wavelength,
                     self.precession_angle,
                     self.shape_factor_model,
-                    self.max_excitation_error,
+                    max_excitation_error,
                     **self.shape_factor_kwargs,
                     )
         elif self.precession_angle > 0 and self.approximate_precession:
diff --git a/diffsims/tests/test_generators/test_diffraction_generator.py b/diffsims/tests/test_generators/test_diffraction_generator.py
index 8655d442..fae195ca 100644
--- a/diffsims/tests/test_generators/test_diffraction_generator.py
+++ b/diffsims/tests/test_generators/test_diffraction_generator.py
@@ -28,15 +28,27 @@
     _average_excitation_error_precession,
 )
 import diffpy.structure
-from diffsims.utils.shape_factor_models import (linear, binary, sinc, sin2c,
-                                                atanc, lorentzian, 
-                                                lorentzian_precession)
+from diffsims.utils.shape_factor_models import (linear, binary, sin2c,
+                                                atanc, lorentzian)
+
 
 @pytest.fixture(params=[(300)])
 def diffraction_calculator(request):
     return DiffractionGenerator(request.param)
 
 
+@pytest.fixture(scope="module")
+def diffraction_calculator_precession_full():
+    return DiffractionGenerator(300, precession_angle=0.5,
+                                approximate_precession=False)
+
+
+@pytest.fixture(scope="module")
+def diffraction_calculator_precession_simple():
+    return DiffractionGenerator(300, precession_angle=0.5,
+                                approximate_precession=True)
+
+
 @pytest.fixture(params=[(300, [np.linspace(-1, 1, 10)] * 2)])
 def diffraction_calculator_atomic(request):
     return AtomicDiffractionGenerator(*request.param)
@@ -96,7 +108,7 @@ def test_z_sphere_precession(parameters, expected):
     assert np.allclose(result, expected)
 
 
-@pytest.mark.parametrize("model", [linear, atanc, sin2c, lorentzian])
+@pytest.mark.parametrize("model", [binary, linear, atanc, sin2c, lorentzian])
 def test_shape_factor_precession(model):
     z = np.array([-0.1, 0.1])
     r = np.array([1, 5])
@@ -133,6 +145,22 @@ def test_matching_results(self, diffraction_calculator, local_structure):
         assert len(diffraction.indices) == len(diffraction.coordinates)
         assert len(diffraction.coordinates) == len(diffraction.intensities)
 
+    def test_precession_simple(self, diffraction_calculator_precession_simple,
+            local_structure):
+        diffraction = diffraction_calculator_precession_simple.calculate_ed_data(
+            local_structure, reciprocal_radius=5.0,
+        )
+        assert len(diffraction.indices) == len(diffraction.coordinates)
+        assert len(diffraction.coordinates) == len(diffraction.intensities)
+
+    def test_precession_full(self, diffraction_calculator_precession_full,
+            local_structure):
+        diffraction = diffraction_calculator_precession_full.calculate_ed_data(
+            local_structure, reciprocal_radius=5.0,
+        )
+        assert len(diffraction.indices) == len(diffraction.coordinates)
+        assert len(diffraction.coordinates) == len(diffraction.intensities)
+        
     def test_appropriate_scaling(self, diffraction_calculator: DiffractionGenerator):
         """Tests that doubling the unit cell halves the pattern spacing."""
         silicon = make_structure(5)