diff --git a/functions.py b/functions.py
index 2050f9a..1b6ada2 100644
--- a/functions.py
+++ b/functions.py
@@ -107,7 +107,7 @@ class Exif:
     Exif-Comment that has been written (incl. radiation)
     '''
 
-    def __init__(self, photo, radiation, latitude, longitude, elevation, dry_run):
+    def __init__(self, photo, dry_run, radiation=False, latitude=False, longitude=False, elevation=False):
         self.write_exif = self._write_exif(photo, radiation, latitude,
                                            longitude, elevation, dry_run)
  
@@ -128,36 +128,45 @@ class Exif:
         second = round((t1 - minute) * 60, 5)
         return (deg, minute, second, loc_value) 
 
-    def _write_exif(self, photo, radiation, latitude, longitude, elevation, dry_run):
+    def _write_exif(self, photo, dry_run, radiation, latitude, longitude, elevation):
 
         metadata = pyexiv2.ImageMetadata(photo)
         metadata.read()
 
-        latitude_degree = self._to_degree(latitude, ["S", "N"])
-        longitude_degree = self._to_degree(longitude, ["W", "E"])
+        if latitude or longitude:
+            latitude_degree = self._to_degree(latitude, ["S", "N"])
+            longitude_degree = self._to_degree(longitude, ["W", "E"])
 
-        # convert decimal coordinates into fractions required for pyexiv2
-        exiv2_latitude = (Fraction(latitude_degree[0] * 60 + latitude_degree[1], 60),
-                          Fraction(int(round(latitude_degree[2] * 100, 0)), 6000),
-                          Fraction(0, 1))
-        exiv2_longitude = (Fraction(longitude_degree[0] * 60 + longitude_degree[1], 60),
-                           Fraction(int(round(longitude_degree[2] * 100, 0)), 6000),
-                           Fraction(0, 1))
+            # convert decimal coordinates into fractions required for pyexiv2
+            exiv2_latitude = (Fraction(latitude_degree[0] * 60 + latitude_degree[1], 60),
+                              Fraction(int(round(latitude_degree[2] * 100, 0)), 6000),
+                              Fraction(0, 1))
+            exiv2_longitude = (Fraction(longitude_degree[0] * 60 + longitude_degree[1], 60),
+                               Fraction(int(round(longitude_degree[2] * 100, 0)), 6000),
+                               Fraction(0, 1))
 
-        # Set new UserComment
-        new_comment = 'Radiation ☢ ' + str(radiation) + ' µS/h'
-        
-        # Exif tags to write
-        metadata['Exif.GPSInfo.GPSLatitude'] = exiv2_latitude
-        metadata['Exif.GPSInfo.GPSLatitudeRef'] = latitude_degree[3]
-        metadata['Exif.GPSInfo.GPSLongitude'] = exiv2_longitude
-        metadata['Exif.GPSInfo.GPSLongitudeRef'] = longitude_degree[3]
-        metadata['Exif.GPSInfo.GPSAltitude'] = Fraction(elevation)
-        metadata['Exif.GPSInfo.GPSAltitudeRef'] = '0'
-        metadata['Exif.Image.GPSTag'] = 654
-        metadata['Exif.GPSInfo.GPSMapDatum'] = "WGS-84"
-        metadata['Exif.GPSInfo.GPSVersionID'] = '2 0 0 0'
-        metadata['Exif.Photo.UserComment'] = new_comment
+            # Exif tags to write
+            metadata['Exif.GPSInfo.GPSLatitude'] = exiv2_latitude
+            metadata['Exif.GPSInfo.GPSLatitudeRef'] = latitude_degree[3]
+            metadata['Exif.GPSInfo.GPSLongitude'] = exiv2_longitude
+            metadata['Exif.GPSInfo.GPSLongitudeRef'] = longitude_degree[3]
+            metadata['Exif.Image.GPSTag'] = 654
+            metadata['Exif.GPSInfo.GPSMapDatum'] = "WGS-84"
+            metadata['Exif.GPSInfo.GPSVersionID'] = '2 0 0 0'
+
+            if not elevation:
+                metadata['Exif.GPSInfo.GPSAltitude'] = Fraction(elevation)
+                metadata['Exif.GPSInfo.GPSAltitudeRef'] = '0'
+        else:
+            latitude_degree = None
+            longitude_degree = None
+
+        if radiation:
+            # Set new UserComment
+            new_comment = 'Radiation ☢ ' + str(radiation) + ' µS/h'
+            metadata['Exif.Photo.UserComment'] = new_comment
+        else:
+            new_comment = None
 
         # Write Exif tags to file, if not in dry-run mode
         if dry_run is not True:
diff --git a/rad_tag.py b/rad_tag.py
index 26efd2d..43d3415 100755
--- a/rad_tag.py
+++ b/rad_tag.py
@@ -90,13 +90,13 @@ for src_photo in args.photos:
     print(photo.get_target_photo, photo.get_date)
 
     # Here the matching magic has to happen
-    latitude = 51.0234024
-    longitude = 7.248347
+    #latitude = 51.0234024
+    #longitude = 7.248347
     radiation = 9001.15
-    elevation = 56.079345703125
+    #elevation = 56.079345703125
     
     # Write exif data
-    exif_tags = Exif(photo.get_target_photo, radiation, latitude, longitude, elevation, args.dry)
+    exif_tags = Exif(photo=photo.get_target_photo, dry_run=args.dry)
     print(exif_tags)
 
 # Print table header