Recommend long manual focus primes for NEX

The longest manual focus lens I own is a Vivitar (Komine) 135mm f/2.8. It is absolutely brilliant, it has the by far best build quality out of all my old MF lenses, and image quality is very good. It is a joy to use.

However, focusing manually at f/2.8 near minimum focusing distance at 135mm is not an easy task. I find I mainly shoot it at f/4 or f/5.6 for portraits and candids, the increased FOV greatly increases my keeper rate.