diff --git a/exif_rad.py b/exif_rad.py
index 8ffc907..be13619 100755
--- a/exif_rad.py
+++ b/exif_rad.py
@@ -6,13 +6,14 @@ DateTimeOriginal from Exif tag to DateTime in a csv log
 of a GeigerMuellerCounter."""
 
 from datetime import datetime
+import os
 import csv
 import argparse
 from PIL import Image
 import piexif
 import piexif.helper
 
-# Constants for GQ geiger counters
+# SIFACTOR for GQ geiger counters
 
 # 300  series: 0.0065   µSv/h / CPM
 # 320  series: 0.0065   µSv/h / CPM
@@ -21,15 +22,18 @@ import piexif.helper
 # 600  series: 0.0065   µSv/h / CPM
 # 600+ series: 0.002637 µSv/h / CPM
 
-SIFACTOR = 0.0065 
-
-parser = argparse.ArgumentParser(description='''A tool that writes 
+parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter, 
+                                 description='''A tool that writes 
     radiation levels (and optionally geocoordinates) to image files 
     and extracts the infos from external sources.''')
+parser.add_argument('-si', '--sifactor', type=float, default=0.0065, 
+                    help='Factor to multiply recorded CPM with.')
 parser.add_argument('csv', metavar='CSV', type=str, 
                     help='Geiger counter history file in CSV format.')
 parser.add_argument('photos', metavar='Photo', type=str, nargs='+', 
                     help='One or multiple photo image files to process.')
+parser.add_argument('-o', '--outdir', type=str, default='.', 
+                    help='Directory to output processed photos')
 
 args = parser.parse_args()
 
@@ -50,7 +54,7 @@ with open(args.csv, "r") as f:
             csvisotime = datetime.fromisoformat(csvrawtime)
             
             if csvisotime == picisotime:
-                rad = round(float(csvrawcpm) * SIFACTOR, 2)
+                rad = round(float(csvrawcpm) * args.sifactor, 2)
                 print("Radiation at time of photo: ", rad, "µS/h")
 
                 # convert str to exif compatible string
@@ -61,5 +65,6 @@ with open(args.csv, "r") as f:
                 # compile and write tags
                 print("Going to write comment: " + new_comment)
                 exif_bytes = piexif.dump(exif_dict)
-                im.save("testdata/test.jpg", exif=exif_bytes)
+                outfile = os.path.join(args.outdir, photo)
+                im.save(outfile, exif=exif_bytes)
                 break