diff --git a/lib/data/permissions_service.dart b/lib/data/permissions_service.dart
index d01e022..6d0e64c 100644
--- a/lib/data/permissions_service.dart
+++ b/lib/data/permissions_service.dart
@@ -1,8 +1,8 @@
 import 'package:permission_handler/permission_handler.dart';
 
 class PermissionsService {
-  
   const PermissionsService();
+
   Future<PermissionStatus> checkCameraPermission() async => Permission.camera.status;
 
   Future<PermissionStatus> requestCameraPermission() async => Permission.camera.request();
diff --git a/lib/providers/metering_screen_layout_provider.dart b/lib/providers/metering_screen_layout_provider.dart
index 965b275..405c1a7 100644
--- a/lib/providers/metering_screen_layout_provider.dart
+++ b/lib/providers/metering_screen_layout_provider.dart
@@ -3,35 +3,6 @@ import 'package:lightmeter/data/models/metering_screen_layout_config.dart';
 import 'package:lightmeter/data/shared_prefs_service.dart';
 import 'package:lightmeter/utils/inherited_generics.dart';
 
-class MeteringScreenLayout extends InheritedModelBase<MeteringScreenLayoutFeature, bool> {
-  const MeteringScreenLayout({
-    required super.data,
-    required super.child,
-    super.key,
-  });
-
-  static MeteringScreenLayoutConfig of(BuildContext context, {bool listen = true}) {
-    if (listen) {
-      return context
-          .dependOnInheritedWidgetOfExactType<
-              InheritedModelBase<MeteringScreenLayoutFeature, bool>>()!
-          .data;
-    } else {
-      return context
-          .findAncestorWidgetOfExactType<InheritedModelBase<MeteringScreenLayoutFeature, bool>>()!
-          .data;
-    }
-  }
-
-  static bool featureOf(BuildContext context, MeteringScreenLayoutFeature aspect) {
-    return InheritedModel.inheritFrom<InheritedModelBase<MeteringScreenLayoutFeature, bool>>(
-      context,
-      aspect: aspect,
-    )!
-        .data[aspect]!;
-  }
-}
-
 class MeteringScreenLayoutProvider extends StatefulWidget {
   final Widget child;
 
@@ -70,3 +41,20 @@ class MeteringScreenLayoutProviderState extends State<MeteringScreenLayoutProvid
     context.get<UserPreferencesService>().meteringScreenLayout = _config;
   }
 }
+
+typedef _MeteringScreenLayoutModel = InheritedModelBase<MeteringScreenLayoutFeature, bool>;
+
+extension MeteringScreenLayout on InheritedModelBase<MeteringScreenLayoutFeature, bool> {
+  static MeteringScreenLayoutConfig of(BuildContext context, {bool listen = true}) {
+    if (listen) {
+      return context.dependOnInheritedWidgetOfExactType<_MeteringScreenLayoutModel>()!.data;
+    } else {
+      return context.findAncestorWidgetOfExactType<_MeteringScreenLayoutModel>()!.data;
+    }
+  }
+
+  static bool featureOf(BuildContext context, MeteringScreenLayoutFeature aspect) {
+    return InheritedModel.inheritFrom<_MeteringScreenLayoutModel>(context, aspect: aspect)!
+        .data[aspect]!;
+  }
+}
diff --git a/lib/screens/metering/bloc_metering.dart b/lib/screens/metering/bloc_metering.dart
index 1b52882..34d5a3c 100644
--- a/lib/screens/metering/bloc_metering.dart
+++ b/lib/screens/metering/bloc_metering.dart
@@ -40,7 +40,7 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
     this.stopType,
   ) : super(
           MeteringDataState(
-            ev: 0.0,
+            ev: null,
             film: _meteringInteractor.film,
             iso: _meteringInteractor.iso,
             nd: _meteringInteractor.ndFilter,
@@ -77,55 +77,75 @@ class MeteringBloc extends Bloc<MeteringEvent, MeteringState> {
   }
 
   void _onStopTypeChanged(StopTypeChangedEvent event, Emitter emit) {
-    stopType = event.stopType;
-    _updateMeasurements();
+    if (stopType != event.stopType) {
+      stopType = event.stopType;
+      _updateMeasurements();
+    }
   }
 
   void _onEquipmentProfileChanged(EquipmentProfileChangedEvent event, Emitter emit) {
     _equipmentProfileData = event.equipmentProfileData;
+    bool willUpdateMeasurements = false;
 
     /// Update selected ISO value, if selected equipment profile
     /// doesn't contain currently selected value
     if (!event.equipmentProfileData.isoValues.any((v) => _iso.value == v.value)) {
       _meteringInteractor.iso = event.equipmentProfileData.isoValues.first;
       _iso = event.equipmentProfileData.isoValues.first;
+      willUpdateMeasurements &= true;
     }
 
     /// The same for ND filter
     if (!event.equipmentProfileData.ndValues.any((v) => _nd.value == v.value)) {
       _meteringInteractor.ndFilter = event.equipmentProfileData.ndValues.first;
       _nd = event.equipmentProfileData.ndValues.first;
+      willUpdateMeasurements &= true;
     }
 
-    _updateMeasurements();
+    if (willUpdateMeasurements) {
+      _updateMeasurements();
+    }
   }
 
   void _onFilmChanged(FilmChangedEvent event, Emitter emit) {
-    if (_iso.value != event.data.iso) {
-      final newIso = IsoValue.values.firstWhere(
-        (e) => e.value == event.data.iso,
-        orElse: () => _iso,
-      );
-      add(IsoChangedEvent(newIso));
+    if (_film.name != event.data.name) {
+      _film = event.data;
+      _meteringInteractor.film = event.data;
+
+      /// If user selects 'Other' film we preserve currently selected ISO
+      /// and therefore only discard reciprocity formula
+      if (_iso.value != event.data.iso && event.data != const Film.other()) {
+        final newIso = IsoValue.values.firstWhere(
+          (e) => e.value == event.data.iso,
+          orElse: () => _iso,
+        );
+        _meteringInteractor.iso = newIso;
+        _iso = newIso;
+      }
+
+      _updateMeasurements();
     }
-    _film = event.data;
-    _meteringInteractor.film = event.data;
-    _updateMeasurements();
   }
 
   void _onIsoChanged(IsoChangedEvent event, Emitter emit) {
-    if (event.isoValue.value != _film.iso) {
-      _film = Film.values.first;
+    /// Discard currently selected film even if ISO is the same,
+    /// because, for example, Fomapan 400 and any Ilford 400
+    /// have different reciprocity formulas
+    _film = Film.values.first;
+
+    if (_iso != event.isoValue) {
+      _meteringInteractor.iso = event.isoValue;
+      _iso = event.isoValue;
+      _updateMeasurements();
     }
-    _meteringInteractor.iso = event.isoValue;
-    _iso = event.isoValue;
-    _updateMeasurements();
   }
 
   void _onNdChanged(NdChangedEvent event, Emitter emit) {
-    _meteringInteractor.ndFilter = event.ndValue;
-    _nd = event.ndValue;
-    _updateMeasurements();
+    if (_nd != event.ndValue) {
+      _meteringInteractor.ndFilter = event.ndValue;
+      _nd = event.ndValue;
+      _updateMeasurements();
+    }
   }
 
   void _onMeasure(MeasureEvent _, Emitter emit) {