I am having trouble with my canon xha1. I was told by a reliable friend to always shoot outdoors with the line setting on instead of mic... When I put my line setting on the my wireless (sennheiser ew 100 g2) will pick up but not my shotgun (azden smgpdII). I did some reasearch and it seems that some mics are "line gradient". Do I have to have one of these mics to shoot on the line setting? I am in the middle of a shoot so any advice would be great ASAP.

Line Gradient is a term that is related to mic construction and directional characteristics, not to the signal level which is 'mic level' or 'line level'

Line level is usually used with devices other than mics which plug into the camera, such as a cd player, or in your case, the receiver for the wireless mic. If your shotgun plugs into yuor camera, the camera should be set to mic, whether you are indoors or out.

The other 'gotcha' in this is that some / most wireless mic receivers can be set to provide an output of 'mic level' or 'line level' and this setting should match what your camera is set for.

HTH

I second that, when using the boom you should set to mic, if using a device that has its own amplifier then you set to line... whatever mode you use you want to aim to have your sound peaking at approximately -12db

This one came in under the radar being reposted from the help files. Your friend was well intentioned but misinformed. Make sure that the mic is always set for mic and not for line in.