I got my preorder of the 70-200mm II a couple days ago and finally got a break in the rain today and some downtime to try and compare it on a 2x TC with the 100-400mm. I used a tripod and tried to keep all settings consistent between the two lenses. I shot RAW, imported into Capture One Pro, and adjusted the white balance to match between the two photos. Focus point is just above the white dot near the center of the image. From the initial set of photos I took, cropping to 100% you can definitely tell that the 2x cuts into the sharpness as compared to the 100-400mm. If you're looking for sharpness/detail at 400mm, the 100-400 clearly wins here when you're pixel peeping. If you're not pixel peeping, it's difficult to tell which lens produced which image. The weight difference between the two setups is pretty hard to ignore though. The 70-200mm with 2x TC is noticeably lighter.
I got my preorder of the 70-200mm II a couple days ago and finally got a break in the rain today and some downtime to try and compare it on a 2x TC with the 100-400mm. I used a tripod and tried to keep all settings consistent between the two lenses. I shot RAW, imported into Capture One Pro, and adjusted the white balance to match between the two photos. Focus point is just above the white dot near the center of the image. From the initial set of photos I took, cropping to 100% you can definitely tell that the 2x cuts into the sharpness as compared to the 100-400mm. If you're looking for sharpness/detail at 400mm, the 100-400 clearly wins here when you're pixel peeping. If you're not pixel peeping, it's difficult to tell which lens produced which image.
