[toni-a]

When you will look back at the images, you will now see that the job you did was not that great 

Obviously, I learnt a lot since then 

I used manual focus on 75-300 because lens  autofocus was very slow, 30D was  not a superb performer anyway, my technique was focus trapping, I focused a point and waited the subject to go there.

As for fast lenses and subject isolation it's  quite a tricky thing, with  the thin depth of field the slightest  focus error will make your picture non usable.

I don't know if the autofocus speed of 70-300 would be fast enough though