If you want something fantastic and easy AND FREE !
Take Kerkythea !
http://www.kerkythea.net/joomla/index.php

I rendered these lenses with it !
http://forums1.caligari.com/truespace/showthread.php?t=5143

Its just about the same quality as Maxwell one of the best renderers out there !
Easy to use and a standalone renderer !
Peter