diff --git a/web/calibrate/FindSafeExposure.ts b/web/calibrate/FindSafeExposure.ts
--- a/web/calibrate/FindSafeExposure.ts
+++ b/web/calibrate/FindSafeExposure.ts
@@ -31,6 +31,7 @@ export class FindSafeExposure {
         break;
       }
     }
+    return this.expo;
   }
   
   step(currentOverexposed: number) {