diff --git a/examples/SelfCalibrationExample.cpp b/examples/SelfCalibrationExample.cpp
index afd63beba..58f59b7e2 100644
--- a/examples/SelfCalibrationExample.cpp
+++ b/examples/SelfCalibrationExample.cpp
@@ -54,11 +54,11 @@ int main(int argc, char* argv[]) {
 
   // Add a prior on pose x1.
   noiseModel::Diagonal::shared_ptr poseNoise = noiseModel::Diagonal::Sigmas(Vector_(6, 0.3, 0.3, 0.3, 0.1, 0.1, 0.1)); // 30cm std on x,y,z 0.1 rad on roll,pitch,yaw
-  graph.push_back(PriorFactor<Pose3>(Symbol('x', 0), poses[0], poseNoise)); // add directly to graph
+  graph.push_back(PriorFactor<Pose3>(Symbol('x', 0), poses[0], poseNoise));
 
   // Simulated measurements from each camera pose, adding them to the factor graph
   Cal3_S2 K(50.0, 50.0, 0.0, 50.0, 50.0);
-  noiseModel::Isotropic::shared_ptr measurementNoise = noiseModel::Isotropic::Sigma(2, 1.0); // one pixel in u and v
+  noiseModel::Isotropic::shared_ptr measurementNoise = noiseModel::Isotropic::Sigma(2, 1.0);
   for (size_t i = 0; i < poses.size(); ++i) {
     for (size_t j = 0; j < points.size(); ++j) {
       SimpleCamera camera(poses[i], K);
@@ -73,8 +73,12 @@ int main(int argc, char* argv[]) {
   noiseModel::Isotropic::shared_ptr pointNoise = noiseModel::Isotropic::Sigma(3, 0.1);
   graph.push_back(PriorFactor<Point3>(Symbol('l', 0), points[0], pointNoise)); // add directly to graph
 
+  // Add a prior on the calibration.
+  noiseModel::Diagonal::shared_ptr calNoise = noiseModel::Diagonal::Sigmas(Vector_(5, 500, 500, 0.1, 100, 100));
+  graph.push_back(PriorFactor<Cal3_S2>(Symbol('K', 0), K, calNoise));
+
   // Create the initial estimate to the solution
-  // Including an estimate on the camera calibration parameters
+  // now including an estimate on the camera calibration parameters
   Values initialEstimate;
   initialEstimate.insert(Symbol('K', 0), Cal3_S2(60.0, 60.0, 0.0, 45.0, 45.0));
   for (size_t i = 0; i < poses.size(); ++i)