Quote Originally Posted by neuroanatomist View Post
To the extent that the additional light from a lens with a wider aperture allows better detection of the contrast, it should mean less hunting.
That was my thought.

I have a feeling that it will be hard to discern with this test whether there is any advantage because of the light. Since certain lenses focus faster, wouldn't they hunt faster? So if a prime finds focus faster than the 24-70 or 24-105mm will it be because of the light or because it is a very fast prime?

At best this might be a good test for the "should I get" the 24-70 or 24-105mm debate.
I think the end answer will be if you want to shoot in the lowest of light bring your primes along.