Could someone please help me with this?

Have recently bought a Canon XM2 and immediately wanted to use my Sennheiser microphone I bought years ago for my previous camcorder a Hi-8 Sony job.

I know the microphone is mono using a (mono) 3.5mm jack plug but on the old camera the sound was distributed on both right and left channels. That is, the stereo jack socket on the old Sony camera was "bridging" the mono input into two channels.

However, on the XM2 I'm only getting a "one channel" sound - and I can't understand why as both camera sockets appear exactly the same.

Thanks in anticipation.

I would guess that your old Sony only had a mono microphone socket and simply distributed the sound to the two channels, but your new XM2 has a stereo input - a 3.5mm Mono jack looks identical to a 3.5mm stereo jack from outside the camera - and the tip of your mono plug is only contacting one channel, I would guess you need a mono to stereo jack plug converter like this :-
http://www.keene.co.uk/cgi-bin/codesearch.pl?KA158

I take your point; I always thought however that a mono jack put through a stereo jack-socket bridged the signals into two (mono) channels.

Thanks for the advice and the link - I'll go and get one!

well no because if you hold a mono jack plug and a stereo jack plug side by side you will see that it would be impossible for a mono plug to connect two channels of a stereo socket, because one of the contacts would be on the body (screen) of the mono plug, or it would be bridging tip to screen.

Thank you again for the reply and advice. I stand corrected.