I'm about to travel to the Southwest US, a place I've been and photographed many times. Whenever I traveled with my 7D, I usually took my 50 mm 1.4 along-- mostly for its low-light versatility. This is my first trip with my 5D MK III. I'm planning to take my 17-40 f/4L for landscapes and my 100 f/2.8L for critter and plant closeups. Space is very limited, and I am thinking of leaving the 50 at home (even though it's not very big). These are my reasons: I try to change lenses as little as possible The difference between 40 mm and 50 mm is not all that great The lens correction in the MK III minimizes the distortion at 40 mm enough for me The MK III has decent IQ at insanely high ISOs, reducing the need for 1.4 low light capability Is the 50 still worth taking? If so, any reason other than the benefit of more options? Any insights and opinions would be most appreciated.