How To Stop The Focus Sound On A Nikon D5100?

So i'm getting one in november and when I get it i need a way to stop that annoying focus sound while making the video, there's got to be somthing out there to stop the sound. I'm a photographer and Nikon is better for photography than Canon. But i still want good video just like Canon

You will have to isolate the microphone from the camera. This is true no matter what dSLR camera you use. On-board microphones will always pick up noises caused by the camera or even the handling of the camera.

Unless you are NOT zooming and have your camera mounted on a fluid head tripod and avoid touching the camera during a take, you are fighting a loosing battle.

Actually as a rule, zoom is rarely used in any case. Just look at any video or motion picture and count how many scenes include a zoom shot. A zoom shot is only used to focus attention to a specific subject in a script to associate it with a specific place AND is uses like an explanation point in writing. Too many explanation points quickly overwhelms the reader (viewer)

Zoom lenses make it easy to select specific focal lengths for framing a shot, but are usually used in single focal length segments of a film

Look at this well scripted video.

Here is one product that does that.

http://www.zoom.co.jp/products/h4n

Look for a book called "The Five C's of Cinematography" Setting up shots usually has little to do with zooming.

All DSLRs whatever brand suffer body/lens noise when using the inbuilt microphone, without exception. The easiest way to start removing it is to use a directional external microphone mounted forward and on a noise deadening mount. That's enough to get rid of any noise transmitted to the inbuilt mics through the body, but you may still get some lens focus noise, this is dependant on the how good the mic is and how loud the focus mechanism on the lens is. So getting a quiet lens would help, or you can always manually focus the lens instead. Beyond this you may want to consider using an external audio recorder and then manually syncing this up with the video.

Manually focusing is not as hard as many people seem to believe, once you get the idea, it only take a couple of minutes to get back into the swing of it - though the larger (small f/number) the aperture the harder it gets.

*There's very little difference between the video quality of consumer targeted Nikon and Canon cameras. In the current generation Sony SLT's and NEX cameras (and Nikons J1 based on the same Sony tech) are the top performers, closely followed by Panasonic Lumix. Nikon is refreshing it's range and more of its consumer cameras are likely to get better video. Canon will almost certainly update it's range some time soon and better video is bound to be on the menu.