diff --git a/mmtwfs/config.py b/mmtwfs/config.py
index ad53630..705a11a 100644
--- a/mmtwfs/config.py
+++ b/mmtwfs/config.py
@@ -340,7 +340,7 @@ def merge_config(*dicts):
             "secondary": "f9",
             "default_mode": "blue",
             # effective wavelength of the thruput response of the system
-            "eff_wave": 600 * u.nm,
+            "eff_wave": 760 * u.nm,
             "lampsrv": "_lampbox._tcp.mmto.arizona.edu",
             "cor_coords": [376.0, 434.0],
             "find_fwhm": 12.0,