You can hear the noise when taking a video w/ NIKON D7000 w/ normal lens. Is there any way to get rid of the noise? Will shotgun mic help? Thanks in advance!
Yes and yes.
Some lenses are quieter but even the AF-S ones make some noise.
The further you place the microphone from the lens, the less sound you will record.
You can even use a wireless microphone with transmitter hooked on the hotshoe and the microphone close to your subjects.
While some lenses will generate more noise than others, the only way to eliminate any focus noise is by using a detached microphone. Any hard link between the camera and the microphone will transmit and amplify the vibration and noise coming from the camera body and the lens. By using a a wire between the camera and the microphone, the noise will only transmit by the air witch will likely be unnoticeable.
The analogy can be tested by pressing the camera directly on you head/hears while focusing. The focus vibration and noise will have a direct link to your head and you should notice is louder.
Also, by using a directional microphone, it will only capture the sound in the direction you point it.