Testing nock travel can be done in many different ways. I choose machine that fixes the riser so that I can SEE the cam(s) at work and realize how they influence the string. Video observation does not 'fix' the riser and is therefore not see how the cam(s) affect the string movement. In other words, in the hands of a standard archer (unlike a machine used with video) the bow's riser will become more 'fixed' and bad nock travel will become more prevalent.
Len,
If I may ask you a question on this subject? I understand your reasoning for wanting to see how the cam(s)' work in relation to the string/nock travel with a fixed position riser but do you think a fixed position riser trully represents what a bow does when it is actually shot? What I am trying to say is that don't we have to take into account that the riser and limbs flex quite a bit when the bow is fired. Wouldn't this affect nock travel?