H–3H Tips on Speedlight Care and Reference InformationTroubleshootingWarning indicator Cause Solution 0Safety circuit activationindicator appears.All functions other thanthe power switch areinoperable because ofpower abnormalities.Turn off the power, removethe batteries, and contactyour retailer or Nikonrepresentative.—The flash-ready indicatorblinks after fi ring.Underexposure may haveoccurred.Use a wider aperture ormove the fl ash unit closerto the subject and reshoot.C-4C-7C-10C-13D-20The remote fl ash unitbeeps for approx.3 seconds.Underexposure may haveoccurred.Use a wider aperture, movethe fl ash unit closer tothe subject or change theposition of the fl ash unitand reshoot.D-20Filter detection failureindicator appears.The attached color fi lter hasnot been detected.Confi rm whether the colorfi lter is correctly attached. E-14There is no fl ash outputthat corresponds with thecamera aperture used.Reset the aperture. —The aperture is not at itsmaximum f-number.Set the maximumf-number. —The camera is turned off. Turn the camera on. —Power zoom function doesnot work properly.Turn the SB-910 off and•on again.If the warning indicator•remains, contactyour retailer or Nikonrepresentative.—