Sound quality is actually dependent on the pre-amps of your recorder, in this case, the pre-amp of your camera, which is not very good. If you're using on-camera mics, for most there'll be auto-gain, means it will bring up the sensitivity of the pre-amp, but the downside here is pretty much the same as increasing the ISO of a DSLR, the higher you go, the more sensitive the pre-amp, the more noise.
At the very least you should have a hotshoe shotgun mic to get rid of most of the noise and have the pickup directed at the source. The recorder option should only be considered if you have access to one or have provision for one. A mixer board at the location is a bigger plus.
I think the issue here is with your pickup of the sound source, not so much the recording.