diff --git a/samples/ctrl_manual_exposure.cc b/samples/ctrl_manual_exposure.cc
index 489b2f3..f7168b7 100644
--- a/samples/ctrl_manual_exposure.cc
+++ b/samples/ctrl_manual_exposure.cc
@@ -40,7 +40,7 @@ int main(int argc, char *argv[]) {
     api->SetOptionValue(Option::GAIN, 24);
     // brightness/exposure_time: range [0,240], default 120
     api->SetOptionValue(Option::BRIGHTNESS, 120);
-    // contrast/black_level_calibration: range [0,255], default 116
+    // contrast/black_level_calibration: range [0,254], default 116
     api->SetOptionValue(Option::CONTRAST, 116);
 
     frame_rate = api->GetOptionValue(Option::FRAME_RATE);