Quote Originally Posted by Richard Lane
Not to confuse you even more, but another lens to consider for FF is the 135mm f/2L.

Keep in mind that the 135 f/2 on ff is basically equivelant to the 85 f/1.2 on a 7D, except with *far* better IQ wide open (or stopped down for that matter ).


A longer lens gives you more background blur at the same f number, and thus more DOF with a given amount of background blur. I would choose the faster lens to get a thin DOF and separate my subject, but a longer one to get more background blur while keeping the subject in focus.


I tend to think f/2 on FF is plenty fast most of the time. For example, John's portraits of the little girl (your daughter, John?) are great as they are, and would not, IMO, have benefited from and even faster lens than the f/2 ffeq he used. If you're not going to shoot faster than f/2, you'll get more bokeh with the 135mm than the 85. If you're not going to shoot faster than f/2.8, you'll get more blur with the 200mm than with the 135 or the 85.


In short, if you want to maximize blur, choose a focal length that lets you use all of your glass.