I have got to stop following POTN. You guys give me too many ideas.
I just placed my order for the 70-200 f/4L. I am currently renting a 70-200 f/2.8L IS. The lens is great, but after using it for a while I have decided the f/4 is better for my shooting. Most my shots are on a tripod, at f/8 or above. In fact, I found my photos from the first day using the lens were not as good as usual - I was playing with the large apertures, and the IS. After that I went back to my normal shooting routines and have been pleased with the lens. Decided the f/4 was plenty for me.
Now I get to play the waiting game. At least I have the rental for another week - my f/4 should arrive before I have to return the rental.
-Ryan



