diff --git a/lib/utils/ev_from_bytes.dart b/lib/utils/ev_from_bytes.dart
index 553702d..9010402 100644
--- a/lib/utils/ev_from_bytes.dart
+++ b/lib/utils/ev_from_bytes.dart
@@ -4,24 +4,29 @@ import 'package:exif/exif.dart';
 import 'package:flutter/foundation.dart';
 import 'package:m3_lightmeter_resources/m3_lightmeter_resources.dart';
 
+const String _isoExifKey = 'EXIF ISOSpeedRatings';
+const String _apertureExifKey = 'EXIF FNumber';
+const String _shutterSpeedExifKey = 'EXIF ExposureTime';
+
 Future<double> evFromImage(Uint8List bytes) async {
   final tags = await readExifFromBytes(bytes);
-  final iso = double.tryParse("${tags["EXIF ISOSpeedRatings"]}");
-  final apertureValueRatio = (tags["EXIF FNumber"]?.values as IfdRatios?)?.ratios.first;
-  final speedValueRatio = (tags["EXIF ExposureTime"]?.values as IfdRatios?)?.ratios.first;
+  final iso = double.tryParse("${tags[_isoExifKey]}");
+  final apertureValueRatio = (tags[_apertureExifKey]?.values as IfdRatios?)?.ratios.first;
+  final speedValueRatio = (tags[_shutterSpeedExifKey]?.values as IfdRatios?)?.ratios.first;
+
   if (iso == null || apertureValueRatio == null || speedValueRatio == null) {
     throw ArgumentError(
-      'Error parsing EXIF: ${tags.keys.join(', ')}',
+      'Error parsing EXIF',
       [
-        if (iso == null) 'EXIF ISOSpeedRatings',
-        if (apertureValueRatio == null) 'EXIF FNumber',
-        if (speedValueRatio == null) 'EXIF ExposureTime',
+        if (iso == null) '$_isoExifKey: ${tags[_isoExifKey]?.printable} ${tags[_isoExifKey]?.printable.runtimeType}',
+        if (apertureValueRatio == null) '$_apertureExifKey: $apertureValueRatio',
+        if (speedValueRatio == null) '$_shutterSpeedExifKey: $speedValueRatio',
       ].join(', '),
     );
   }
 
-  final aperture = apertureValueRatio.numerator / apertureValueRatio.denominator;
-  final speed = speedValueRatio.numerator / speedValueRatio.denominator;
+  final aperture = apertureValueRatio.toDouble();
+  final speed = speedValueRatio.toDouble();
 
   return log2(math.pow(aperture, 2)) - log2(speed) - log2(iso / 100);
 }