So, a bunch of you asked that I follow through with my musing about testing the 7D2 versus the 1DX versus the 5D4 on low-light, reach-limited circumstances. The three cameras approach this problem with very different advantages.
I ran some very small tests today and it was interesting. The upshot was that, indeed, the 5D4 is likely to be my new wildlife camera under these circumstances. The catch: there are different sets of circumstances under which each camera is best.
The setup:
- 100-400 II placed on a sturdy tripod
- Shady, wooded stone wall setting demanding at least 1600 ISO (also did well-lit set; more on that later)
- All shots manually focused via liveview with magnification
- With the 5D4, which can autofocus with f/8 on most points, I put the 1.4xIII TC on the lens (note, the difference in field of view between the crop camera at 400 versus the full frame + 1.4x at 400 was not much at all). With the 1DX, I tried it both with and without the TC. As a practical matter, with just the center point able to focus at f/8, I'm not going to keep the TC on the lens with the 1Dx if I think I'll be shooting anything that moves.
- The 7D2 was limited to 1600 ISO, and the two full frame cameras were pushed to 3200, which is a realistic setting in these sorts of shooting conditions, especially given that they were shooting f/8 versus the 7D2's f/5.6.
POOR LIGHT RESULTS:
1) Here is the main result: when you have both low light and you need more reach, then the two full frame cameras do better than the 7D2. This was true both when I had them on the 1.4x TC III and when I used them bare. The full frame IQ advantage in low light just overpowered any crop reach advantage the 7D2 had.
2) Between the two full frame cameras, the 1DX shooting at 400mm without a TC (realistic conditions) did better than the 5D4, even when the picture was upsampled to the same field of view. Stick a TC on the 1DX, and it also out-resolved the 5D4 in low light just a bit. I don't consider a TC on the 1DX realistic, though because of the lack of focus points at f/8. These differences were very, very small, and among multiple shots done, the answer sometimes shifted based probably on slight variations of focus sharpness. Interestingly, I did some bare lens tests between the two of them later in even lower light and the 5D4 had better quality, largely due to significantly less noise.
GOOD LIGHT RESULTS:
1) The 7D2 beat both full frame bodies. This surprised me in the degree to which it was better when zoomed in to 1:1 pixel ratio. In retrospect, I'd like to test the 5D4 without the TC against the 7D2 in good light. It may be that the TC slightly lessened the IQ, disallowing the 30 megapixel advantage from fully tolling. But, then again, 50 percent linear advantage in pixels isn't much of an advantage versus a 1.6x crop factor, which is geometric in how it affects the image.
2) Among the two full frame bodies, the 5D4 with 1.4x TC bested the 1Dx shooting the lens bare in good light. The megapixel advantage also tipped things in favor of the 5D4 in good light when the 1DX also had the TC on.
THE UPSHOT:
In bad light, the order of most desirable camera for image quality is 1DX, 5D4 + 1.4xTCIII and then 7D2. Put these bodies in good light, however, and the order reverses to 7D2, 5D4 + 1.4xTCIII, and then 1Dx. I need to do more testing in other situations to be confident in these results. This is all a first impression.
I was thinking of selling my 1DX, but now I'm not so sure. Between it's incredible low light performance and the 12 fps, that would be a shame to lose. The decision will probably come down to my judgement of how good the autofocus is on the 5D4 with the TC attached. I have a very good impression of it right now, but I haven't yet had the opportunity to really stress it with birds in flight, etc.
At some point in the future I will do similar tests with more varied setups and save some comparison images to post.
