Camera problem or Mic problem
 

I was shooting a company event on Sunday and I was using my VX2100 with my Sennheiser ew112 wireless mic. Here is my problem; Every time I used the camera focus I got some interference in my headphones, which got recorded on the tape. When I changed my setting on the cam to Auto focus, I got the interference even more. I went into the settings on the cam and changed from Auto Mic or Manual Mic. It cut down on the interference a little but it was still there. I know it’s not the Mic, it worked prefect with my other cam (GL2)

Bottom line is every time the camera’s focus was used, I got the hum sound in my headphones and on my tape. Has anyone ever had this problem?

Gary

Try moving your receiver away from the camera. Are you running your camera on Battery or AC power?

Andy

This sounds like a classic case of driving the focus motor is causing electrical noise which shows up in the audio circuits.

If the focus motor is more active (Auto focus) you are getting more noise.

Putting it to manual mic. gain means quiet sections aren't getting boosted so much, so the electrical noise isn't so obvious.

Sounds like the GL2 has better electrical isolation of power from audio.

This is similar to something I've noticed in my old vintage 2000 Sony TRV-320 consumer cam.
If I shoot and capture directly to my laptop, I get better audio than if I stick a tape in the camcorder and record to tape.
My assumption is that driving the tape motor/transport mechanism is causing electrical noise that shows up in the audio, especially in quiet sections.
With that cam, switching to manual audio gain isn't even an option :-(

Andy, it does it on AC power or Battery

I get the exact problem with my Panasonic DVX-100a. It's only noticable when it's on auto focus and keeping it on manual there's no problem. I use the focus ring instead of the push/auto button as well to keep the electrical noise down. Noise reduction tools usually makes things better in post.

Isolating your wireless system
 

On my old XL1S the wireless system mounted on the back (the same with my current JVC HD-100U). Try and moving the wireless unit away from the zoom motor and see if you still get the audio noise. Mounting on top of the camera might be too close to the focus or zoom motors.

Mark, I have my wireless unit mounted on one of my tri-pod legs. I have been using this set-up for over 3 years and its just now acting up. I thinking it may be my camera

Camera Problem
 

Are you using different power source / batteries or have you had the camera in a wet enviorment? How is the wireless unit connected to the camera? Some time I get static and need to change to a different freq. it might be a cableing problem, can you borrow a different wireless unit to test with? Is it connected to your camera with a XLR or 1/8th inch plug? If it is a 1/8 plug, it might be damaged at the connector or the plug, I would try and isolate your problem at the weakest point, it might be a loose grounding connector in the plug or the wireless wire.

Try using a different mic. If the noise persists with a wired mic, or even the internal mic-then I would say your camera is a fault. If so, there is a particular audio problem with the VX I would be looking at. If the other mics work without problem, then I would think the wireless is bad or being interfered with.