Peacefield wrote in post #17084465
In favor of buying the 135L, it's probably one of the best values in the entire L line. Sample photos I've seen from others are stunning. And it would be a better outdoor portrait focal length than my current 85.
The things that hold me back?
One is the perennial talk about an IS version coming soon. IS would be great on a lens of this focal length. But I can safely assume that such a lens will not be available at such a "modest" price.
But here's my bigger question. I own the 85L. Love it on a 5D3. Put it on my 50D body and that beautiful lens has essentially become 135mm. But I have to believe that a 135 on the 5D3 will produce images more beautiful than an 85 on an older crop body, no?
I don't know that the 135L will take "more beautiful" pictures than the 85L, in fact, both lens are capable of equally stunning images. I personally would not hold out for an IS version. The lens will likely be bigger, heavier, and most certainly in the $2,000 range. Moreover, I've found that I tend to want my shutter speed up around 1/125 to 1/250, regardless of focal length or IS, when I am shooting people who are not staying perfectly still, ie. just about any session/event outside of strict portrait work.
If shallow DOF is what you're after, again, both lens do this well. The 135 will give you a more shallow DOF by about 0.1inch with a subject at about 10ft. So the 135 wins by a thin margin.
If you are more interested in low-light capability, then the 85L wins hands-down for several reasons. You can use a lower shutter speed without camera shake/blur because of the shorter focal length, and you get an additional 1.3 stops of light with the f/1.2 vs the f/2.
If you are looking for a lens to use with moving subjects (children, sports, pets, etc) then the 135L wins big. The 85 focuses slowly, sometimes painfully slow.