diff --git a/notebooks/pnCCD/Characterize_pnCCD_Dark_NBC.ipynb b/notebooks/pnCCD/Characterize_pnCCD_Dark_NBC.ipynb
index 13e9c89e6f6571a37a349341eb97d114dabc14fa..f3e8d5cf8d7bdb397b27b50d376eedab3058c9ff 100644
--- a/notebooks/pnCCD/Characterize_pnCCD_Dark_NBC.ipynb
+++ b/notebooks/pnCCD/Characterize_pnCCD_Dark_NBC.ipynb
@@ -58,7 +58,7 @@
     "sigmaNoise = 10.  # pixels whose signal value exceeds sigmaNoise*noise will be considered as cosmics and are masked\n",
     "bad_pixel_offset_sigma = 4.  # any pixel whose offset beyond this standard deviations is a bad pixel\n",
     "bad_pixel_noise_sigma = 4.  # any pixel whose noise beyond this standard deviations is a bad pixel\n",
-    "max_trains = 0  # Maximum number of trains to use for dark processing. Set to 0 to process all trains.\n",
+    "max_trains = 500  # Maximum number of trains to use for dark processing. Set to 0 to process all trains.\n",
     "min_trains = 1  # Minimum number of trains to proceed with dark processing.\n",
     "\n",
     "# Don't delete. myMDC sends this parameter by default.\n",