diff --git a/spectur_live_view.py b/spectur_live_view.py
index 3ca8297..dfa2494 100644
--- a/spectur_live_view.py
+++ b/spectur_live_view.py
@@ -145,23 +145,25 @@ def get_next_image(driver, cookies):
         battery_str = driver.find_element_by_id('battery').text
         f.write('{}\t{}\n'.format(t_local.isoformat(), battery_str[:-1]))
 
-    # Update counter
-    t.append(time.mktime(t_local.timetuple()))
+    # Update time counter
+    current_time = float(time.mktime(t_local.timetuple()))
+    if current_time not in t:
+        t.append(current_time)
 
     # Count images collected
     n = len(t)
 
-    if n > 1:
+    if n > 2:
         # Get frames per second
         fps = 1 / np.median(np.diff(t))
 
         # Count dropped frames
-        n_dropped = np.max([0, int(fps * (t[-1] - t[0]) - n + 1)])
+        n_expected = fps * (t[-1] - t[0])
+        n_dropped = np.max([0, int(n_expected - n + 1)])
 
-        print('{}  total images: {}  fps: {}  dropped frames: {}'.format(
-            t_local.isoformat(), n, fps, n_dropped),
-              end='\r',
-              flush=True)
+        msg = '{}  total images: {}  fps: {}  dropped frames: {}'.format(
+            t_local.isoformat(), n, fps, n_dropped)
+        print(msg, end='\r', flush=True)
 
 
 def main():