I can't afford to buy a wireless system right now so have been quite successfully experiementing using a lav mic attached to my Edirol R0-9 then using a clapper for lip synch in post.

The mic I've been 'playing with' is just a cheap and nasty thing I had lying around so need to get a new mic but am confused as to which type I need for the job: a cardioid unidirectional or omni directional microphone?

It is simply for presenting to camera some of the time this may be in noisy surroundings.

Thank you

The 'normal' lav for film/video dialog would be an omni. Cardioids are problematic as normal head movement on the part of the subject can cause them to go on and off mic, leading to dialog that changes in timbre. Cardioid and the few hypercardioid lavs are mainly used in sound reinforcment scenarios where control of feedback through a PA system is a problem. The directivity of the mic helps prevent feedback and that offsets the drawback of the sound quality changing as the speaker looks in different directions.

Philip,

If you're in the market for a new lav mic you could do a lot worse than look at the new Rode Lav mic (it's about £150-160 ish at the moment in the UK from memory). Not sure if that's too steep for you. Buy it with the connector you need now and that can easily be changed if needed when you can afford a wireless unit. I don't have it (yet) but it's on my 2011 must have purchase list!

There is an excellent video review/thread in this section of DVinfo comparing it to some cheapo and much more expensive alternatives. Link below.

http://www.dvinfo.net/forum/all-things-audio/486339-lav-shootout-rode-tram-sanken-sennheiser.html

Remember, with mics, you only want to/need to buy them once so buy well and it'll serve you a lifetime.