Index: trunk/ppStack/src/ppStackPrepare.c
===================================================================
--- trunk/ppStack/src/ppStackPrepare.c	(revision 34095)
+++ trunk/ppStack/src/ppStackPrepare.c	(revision 34800)
@@ -132,4 +132,5 @@
     psVectorInit(options->inputMask, 0);
     options->exposures = psVectorAlloc(options->num, PS_TYPE_F32);
+
     psVectorInit(options->exposures, NAN);
 
@@ -150,4 +151,8 @@
 
         options->exposures->data.F32[i] = psMetadataLookupF32(NULL, cell->concepts, "CELL.EXPOSURE");
+	if ((options->exposures->data.F32[i] == 0)||
+	    (!(isfinite(options->exposures->data.F32[i])))){
+	  options->exposures->data.F32[i] = psMetadataLookupF32(NULL,recipe,"DEFAULT.EXPTIME");
+	}
         options->sumExposure += options->exposures->data.F32[i];