Why would you do that? I guess you could, but the GH1/2's audio path is very inferior to the H4n, and IMO only good enough for checking sync, so unless you're recording the audio on the h4n from a radio mic and it's not audible on the camera's mic (ie making it difficult to sync because you can't hear both recordings), there's no particular reason to want to feed the audio into its input rather than just use the camera mic as a sync reference.

So apart from the case above I can't concieve a reason to connect them together, but someone else may have different experience.

@LPowell Good point!

It is worth to control H4n and Panasonic with one button - to easier synchronize MTS and WAV files and save some time in post.

I worked for a while to program uC and did reverse engineering of H4n interface measuring communication commands with oscilloscope - I can share data if anyone interested.

You need 3 control lines to have such system working properly - one to set resistance to start/stop Panasonic, this is easy - 2nd for TX to H4n and you need it to sent 2 separate commands (START twice to start recording and STOP to produce separate WAV for easier matching with video files). 3rd line is RX from H4n - is is used to control LEDs on the remote and also to register remote control in H4n.

I just stack on this registration message - some timings have to be corrected it worked properly, later I had to return oscilloscope and stopped working on this.

Other option is to use remote control - soldier cables to START/STOP pins however you have to press it twice to start so this is not as good solution as above when you press once one button to start and stop.

This is my first post so it is good opportunity to thank Vitaliy for hack and this forum for sharing ideas, your achievements and good advices - the only thing I don't like is the name for firmware hacks - Stalin, Lenin - why not Hitler then?

http://www.flickr.com/photos/emboschma/6038471527/in/set-72157625946911686

New audio-setup - works/sounds great!

Love the H4N, recorded this acoustic session with it.
Guitar recorded in stereo with the H4N.
Voice recorded with a Cardioid Condenser Microphone Studio Projects B1 attached to H4N.

also interested in an answer to that question, @petee28.

@Rambo Looks like Panasonic's anamorphic lens. http://goo.gl/i8mJu

Panasonic AG-LA7200 Anamorphic Lens Adapter AG-LA7200G B&H Photo

How bad do you guys really think would the audio be on a setup like suggested by the TO: Mic to H4N -> LineOut -> SescomCable -> GH2 on lowest audio gain?

I am thinking of doing it that way for run'n'gun gigs for extra fast delivery and my tests so far revealed differences in sound yes, but not neccessarily in quality. I mean, sure the H4n has better audio by specs. But who would ever notice a difference?

For my film projects I´d do dual system.

After some testing with that exact same setup (Mic, H4N, Sescom, GH2 (turned down to 1 on audio levels) I am most confident that this in-camera audio is perfectly suited for everything web-video-related, as long as it is simple audio as in Interviews in controlled closed environments.

It saves you one step in your pipeline and no one on his or her notebook speakers or logitech sound system etc. will ever say "dang, that´s crappy in-camera audio!".

For myself I draw the line where I am in danger of having to really tweak the audio in post (noise reduction, heavy EQs...) or of course for broadcast delivery and further up.

@Fearseeker

Is this what you're looking for?

Sescom 3.5mm Line to Mic with 25dB Attenuator for Zoom H4N/H1 with Headphone Monitoring Jack
http://www.markertek.com/Cables/Audio-Cables/DSLR-Audio-Cables/Sescom/LN2MIC-ZMH4-MON.xhtml

@spirit
This seems to be exactly what I need, thank you!

Thanks Phenixzone!

@petee28 @csync I use a Sound Devices MM-1 as I only need one channel, and the sound quality is fantastic, quite a step-up from the preamps in the H4 or most cameras. If you need two channels, I'd suggest the MixPre-D.