So I just got the 1.4x III teleconverter for my 70-200 f/4L IS and was also thinking of renting the 100-400L to take with. Should I not even bother and use the 70-200 with the extender?
I've been looking at the 100-400 sample gallery and it's ok and nothing beats the sharpness of my 70-200 f4, I don't even think my primes are as sharp.
conditions: whale watching, rocking boat, early afternoon plenty of light.

