perkyporker said:
While it might yield a useful reference, 16mm soundtracks have a fairly limited frequency response – around 150 to 5000 Hz with a dynamic range of about 40 dB. A 35mm Academy mono optical track is more like 45 to 8000 Hz with a dynamic range of around 48 dB.
From wikipedia, the linear track on a VHS tape has a frequency response of 100 to 10000Hz, so was probably a better source for the audio - certainly in terms of high-frequency content.
While it is true that video has a wider frequency response, I think that a film's optical audio is worth grabbing. I've come to really like working with optical film audio a lot. In my experience, optical audio doesn't degrade over time in the same way as magnetic audio. In fact, it barely degrades at all. Prints that are heavily scratched, pink, even vinegary, generally have audio tracks that sound largely the same as they did when they were new. And they don't develop hiss, wow/flutter, and other stuff that need to be filtered out of magnetic audio. Optical soundtracks are extremely easy to work with in post production, since they are generally well saturated and don't require much "work" to get to sound good. Removing hiss from old video can lead to metallic artifacts, or just needing to leave the hiss in which can make for distracting listening. Severe warpage can cause trouble in film, of course, but that's true in video too. Capturing optical sound also tends to result in hum, but in my experience hum is very easy to remove, whereas hiss is much harder to remove. In other words, both forms of media have their strengths.