diff --git a/include/aare/CalculateEta.hpp b/include/aare/CalculateEta.hpp
index 2797233..1566de5 100644
--- a/include/aare/CalculateEta.hpp
+++ b/include/aare/CalculateEta.hpp
@@ -64,31 +64,78 @@ calculate_eta2(const Cluster<T, ClusterSizeX, ClusterSizeY, CoordType> &cl) {
     eta.sum = max_sum.first;
     auto c = max_sum.second;
 
+    size_t cluster_center_index =
+        (ClusterSizeX / 2) + (ClusterSizeY / 2) * ClusterSizeX;
+
     size_t index_bottom_left_max_2x2_subcluster =
         (int(c / (ClusterSizeX - 1))) * ClusterSizeX + c % (ClusterSizeX - 1);
 
-    if ((cl.data[index_bottom_left_max_2x2_subcluster] +
-         cl.data[index_bottom_left_max_2x2_subcluster + 1]) != 0)
-        eta.x = static_cast<double>(
-                    cl.data[index_bottom_left_max_2x2_subcluster + 1]) /
-                static_cast<double>(
-                    (cl.data[index_bottom_left_max_2x2_subcluster] +
-                     cl.data[index_bottom_left_max_2x2_subcluster + 1]));
+    // check that cluster center is in max subcluster
+    if (cluster_center_index != index_bottom_left_max_2x2_subcluster &&
+        cluster_center_index != index_bottom_left_max_2x2_subcluster + 1 &&
+        cluster_center_index !=
+            index_bottom_left_max_2x2_subcluster + ClusterSizeX &&
+        cluster_center_index !=
+            index_bottom_left_max_2x2_subcluster + ClusterSizeX + 1)
+        throw std::runtime_error("Photon center is not in max 2x2_subcluster");
 
-    if ((cl.data[index_bottom_left_max_2x2_subcluster] +
-         cl.data[index_bottom_left_max_2x2_subcluster + ClusterSizeX]) != 0)
-        eta.y =
-            static_cast<double>(
-                cl.data[index_bottom_left_max_2x2_subcluster + ClusterSizeX]) /
-            static_cast<double>(
-                (cl.data[index_bottom_left_max_2x2_subcluster] +
-                 cl.data[index_bottom_left_max_2x2_subcluster + ClusterSizeX]));
+    if ((cluster_center_index - index_bottom_left_max_2x2_subcluster) %
+            ClusterSizeX ==
+        0) {
+        if ((cl.data[cluster_center_index + 1] +
+             cl.data[cluster_center_index]) != 0)
+
+            eta.x = static_cast<double>(cl.data[cluster_center_index + 1]) /
+                    static_cast<double>((cl.data[cluster_center_index + 1] +
+                                         cl.data[cluster_center_index]));
+    } else {
+        if ((cl.data[cluster_center_index] +
+             cl.data[cluster_center_index - 1]) != 0)
+
+            eta.x = static_cast<double>(cl.data[cluster_center_index]) /
+                    static_cast<double>((cl.data[cluster_center_index - 1] +
+                                         cl.data[cluster_center_index]));
+    }
+    if ((cluster_center_index - index_bottom_left_max_2x2_subcluster) /
+            ClusterSizeX <
+        1) {
+        assert(cluster_center_index + ClusterSizeX <
+               ClusterSizeX * ClusterSizeY); // suppress warning
+        if ((cl.data[cluster_center_index] +
+             cl.data[cluster_center_index + ClusterSizeX]) != 0)
+            eta.y = static_cast<double>(
+                        cl.data[cluster_center_index + ClusterSizeX]) /
+                    static_cast<double>(
+                        (cl.data[cluster_center_index] +
+                         cl.data[cluster_center_index + ClusterSizeX]));
+    } else {
+        if ((cl.data[cluster_center_index] +
+             cl.data[cluster_center_index - ClusterSizeX]) != 0)
+            eta.y = static_cast<double>(cl.data[cluster_center_index]) /
+                    static_cast<double>(
+                        (cl.data[cluster_center_index] +
+                         cl.data[cluster_center_index - ClusterSizeX]));
+    }
 
     eta.c = c; // TODO only supported for 2x2 and 3x3 clusters -> at least no
                // underyling enum class
     return eta;
 }
 
+// Dont get why this is correct - photon center should be top right corner
+template <typename T>
+Eta2<T> calculate_eta2(const Cluster<T, 2, 2, int16_t> &cl) {
+    Eta2<T> eta{};
+
+    if ((cl.data[0] + cl.data[1]) != 0)
+        eta.x = static_cast<double>(cl.data[1]) / (cl.data[0] + cl.data[1]);
+    if ((cl.data[0] + cl.data[2]) != 0)
+        eta.y = static_cast<double>(cl.data[2]) / (cl.data[0] + cl.data[2]);
+    eta.sum = cl.sum();
+    eta.c = cBottomLeft; // TODO! This is not correct, but need to put something
+    return eta;
+}
+
 // calculates Eta3 for 3x3 cluster based on code from analyze_cluster
 // TODO only supported for 3x3 Clusters
 template <typename T> Eta2<T> calculate_eta3(const Cluster<T, 3, 3> &cl) {
diff --git a/include/aare/ClusterVector.hpp b/include/aare/ClusterVector.hpp
index cc88256..e91cb6d 100644
--- a/include/aare/ClusterVector.hpp
+++ b/include/aare/ClusterVector.hpp
@@ -47,7 +47,7 @@ class ClusterVector<Cluster<T, ClusterSizeX, ClusterSizeY, CoordType>> {
      * @param frame_number frame number of the clusters. Default is 0, which is
      * also used to indicate that the clusters come from many frames
      */
-    ClusterVector(size_t capacity = 300, uint64_t frame_number = 0)
+    ClusterVector(size_t capacity = 1024, uint64_t frame_number = 0)
         : m_frame_number(frame_number) {
         m_data.reserve(capacity);
     }
diff --git a/src/CalculateEta.test.cpp b/src/CalculateEta.test.cpp
index 59a616e..cdec79b 100644
--- a/src/CalculateEta.test.cpp
+++ b/src/CalculateEta.test.cpp
@@ -26,15 +26,15 @@ auto get_test_parameters() {
             ClusterTypes{Cluster<int, 3, 3>{0, 0, {1, 2, 3, 4, 5, 6, 1, 2, 7}}},
             Eta2<int>{6. / 11, 2. / 7, corner::cTopRight, 20}),
         std::make_tuple(ClusterTypes{Cluster<int, 5, 5>{
-                            0, 0, {1, 6, 7, 6, 5, 4, 3, 2, 1, 8, 8, 9, 2,
+                            0, 0, {1, 6, 7, 6, 5, 4, 3, 2, 1, 2, 8, 9, 8,
                                    1, 4, 5, 6, 7, 8, 4, 1, 1, 1, 1, 1}}},
-                        Eta2<int>{9. / 17, 5. / 13, 8, 28}),
+                        Eta2<int>{8. / 17, 7. / 15, 9, 30}),
         std::make_tuple(
             ClusterTypes{Cluster<int, 4, 2>{0, 0, {1, 4, 7, 2, 5, 6, 4, 3}}},
-            Eta2<int>{7. / 11, 6. / 10, 1, 21}),
+            Eta2<int>{4. / 10, 4. / 11, 1, 21}),
         std::make_tuple(
             ClusterTypes{Cluster<int, 2, 3>{0, 0, {1, 3, 2, 3, 4, 2}}},
-            Eta2<int>{3. / 5, 4. / 6, 1, 11}));
+            Eta2<int>{3. / 5, 2. / 5, 1, 11}));
 }
 
 TEST_CASE("compute_largest_2x2_subcluster", "[eta_calculation]") {