« on: December 21, 2014, 06:02:27 PM »
My 7D II arrived yesterday, and I did a series of experiments to decide when to use it rather than the 5D III and with what lenses and with or without TCs.
First I did a series of shots with the iso12233 chart at distance where 100-400 II on the 5DIII was on the verge of being resolved (not close up like with TDP, and all the shots were from the same distance, and not at different distances as done by TDP for the chart to fill the frame). I compared the 300mm f/2.8 with the 100-400.
a) The bare 300mm on the 7DII outresolved the 100-400 on the 5DIII, as expected, as did the 100-400 on the 7D II.
b) The 100-400 is not as good as the 300/2.8 + 1.4xTC, but is still a very good performer.
c) The 100-400 + 1.4xTC outresolved the bare 100-400.
The next question is as the 100-400 + 1.4xTC outresolved the bare 100-400 on the 7D II, should I always use the TC for bird photography? For the 300mm on the 5DIII, I always use the 2xTC at 600mm and f/5.6. But, there are real differences for the 100-400 on the 7DII - addition of the TC increases the f number to 8, affecting the AF and gives a very narrow field of view from the equivalent of a 900mm on FF. In the next collage, I compared the effect of the TC closer to the iso12233 chart where resolution was not as critical. There isn't much difference between the 100-400 + 1.4xTC (at f/8) and the bare 100-400 (f/5.6) upresolved 1.4x using PS. So, I argue that using the bare 100-400 I would be losing a small amount of resolution but would be gaining 1 stop in iso, better AF, less effects from camera shake and, also very important, a wider field of view. My conclusion is that I will use the 100-400mm bare on the 7D II, with a fov of a 640mm on a FF.
Edit - I posted this reply to weixing within seconds of wickidwombat's - and clearly agree with him. My combos are going to be the 5DIII + 300mm+2xTC for optimal (for me) or the 7D II +100-400 II for longer hikes or travel, what luxury!