I am just getting started professionally and want to make the right decision. It has been a hobby for years and ready to invest in a better camera. I have an OLD canon that I have been using and was offered a canon 5D at a good deal, but wondering if I should double the price and go for the Mark ii? Any thoughts? I do wedding (inside usually pretty dark so the higher ISO is exciting to me) Mine currently only goes to 1600. I also do infant/children photography mostly.