Index: trunk/ppStack/src/ppStackLoop.c
===================================================================
--- trunk/ppStack/src/ppStackLoop.c	(revision 19770)
+++ trunk/ppStack/src/ppStackLoop.c	(revision 20427)
@@ -318,4 +318,36 @@
                 }
                 indSources->data[index] = psMemIncrRefCounter(sources);
+
+
+                // Calculate zero points if we don't trust the source lists
+                if (psMetadataLookupBool(NULL, recipe, "ZP")) {
+                    psTrace("ppStack", 2, "Photometering input %d of %d....\n", index, num);
+                    pmFPAfileActivate(config->files, false, NULL);
+                    fileActivationSingle(config, convolveFiles, true, index);
+                    pmFPAfile *file = pmFPAfileSelectSingle(config->files, "PPSTACK.INPUT",
+                                                            index);// File of interest
+                    pmFPAview *view = filesIterateDown(config);
+                    if (!view) {
+                        psFree(globalSources);
+                        psFree(indSources);
+                        psFree(targetPSF);
+                        return false;
+                    }
+
+                    pmReadout *ro = pmFPAviewThisReadout(view, file->fpa); // Readout of interest
+
+                    if (!ppStackInputPhotometry(ro, sources, config)) {
+                        psError(PS_ERR_UNKNOWN, false, "Unable to do photometry on input sources");
+                        psFree(globalSources);
+                        psFree(indSources);
+                        psFree(targetPSF);
+                        return false;
+                    }
+
+                    psFree(view);
+                    filesIterateUp(config);
+                }
+
+
 #ifdef TESTING
                 ppStackSourcesPrint(sources);