Index: trunk/MagicSoft/Mars/mcalib/MHCalibrationTestCam.cc
===================================================================
--- trunk/MagicSoft/Mars/mcalib/MHCalibrationTestCam.cc	(revision 4154)
+++ trunk/MagicSoft/Mars/mcalib/MHCalibrationTestCam.cc	(revision 4155)
@@ -419,4 +419,9 @@
       fRmsMeanPhotPerArea  [j]  /=  numaidx[j]-1.;
       fRmsSigmaPhotPerArea [j]  /=  numaidx[j]-1.; 
+
+      if (fRmsMeanPhotPerArea  [j] > 0.)
+        fRmsMeanPhotPerArea  [j]  =  TMath::Sqrt(fRmsMeanPhotPerArea  [j]);
+      if (fRmsSigmaPhotPerArea [j] > 0.)
+        fRmsSigmaPhotPerArea [j]  =  TMath::Sqrt(fRmsSigmaPhotPerArea [j]);
   }