The gear arrived a day early (thank you lens rentals!) so I got a little time with it in the back yard before it got too dark.
The first thing is, of course, weight. The a6400 (sd card) + 1.4x + 100-400 is only 2219g, compared to a6400 + mc11 + siggy 150-600 C at 2649g vs d850 (xqd card) + grip + EN-EL18c + Tammy 150-600 g2 at 3594g. That 1.0 - 1.4kg is very noticable.
The a6400 body is, for me, almost too small for my hand. I might add the vello grip just for more to hold on to, though with a big lens with tripod foot most of the holding is in the left hand anyway.
I shot mostly with the Sig 150-600C. it did not feel too off balance and handled pretty well. Focus seemed a little slow, but that might be pilot error until I get all the a6400 settings figured out. It was also just before sunset so the lighting was not too bright. I also need to sort out AF-C vs DMF vs various zones vs tracking. I didn't see a built-in help button to describe a setting like on the Nikon.
One of the biggest problems with the a6400 was the viewfinder / monitor switching. I would see a BIF (crow) and bring the camera up to my face and would miss the bird while the VF/monitor switch. I assume there's a setting to force it to VF only, but I could not find it.
Another issue with the EVF is that I have a hard time finding out-of-focus subjects, like going from near focus (say 10m) to BIF at a distance. It all gets blurred out. I also have this problem with other EVFs, not just the a6400. I find the optical VF easier in that regard.
The subject tracking seemed to work pretty well, but I didn't have much to test it with. I look forward to trying it on some sea birds tomorrow.
I mostly tried the 100-400 when it was getting pretty dark. With the TC on the focus was slow and hunted. Without the TC, it was pretty fast and didn't hunt. I'll need to try it with better lighting with actual subjects not just kitchen boxes.
I'll keep posting more updates as I get more experience with the gear. I've not even looked at the photos in lightroom yet.
.....The first thing is, of course, weight. The a6400 (sd card) + 1.4x + 100-400 is only 2219g, compared to a6400 + mc11 + siggy 150-600 C at 2649g vs d850 (xqd card) + grip + EN-EL18c + Tammy 150-600 g2 at 3594g. That 1.0 - 1.4kg is very noticable.....
The need for the battery grip to get to 9fps and the extra weight is one of the prime reasons ultimately why I didn't go with the D850 - the other being the slightly lesser AF performance compared to the D500 /D5.
......Another issue with the EVF is that I have a hard time finding out-of-focus subjects, like going from near focus (say 10m) to BIF at a distance. It all gets blurred out. I also have this problem with other EVFs, not just the a6400. I find the optical VF easier in that regard.....
Even OVF's can have episodes of blurring when the lens goes on a big hunt, though with the OVF there's probably more margin of error (dof) to keep track of a subject even if the lens isn't perfectly in focus.
I imagine a completely lost blur-out in an EVF could mean major annoyance and lost shot opportunities .....
I spent another bit of time in the back yard comparing the 100-400 vs 150-600 C on the a6400. I really do notice the weight and torque differences between the two. The 100-400 is much easier to shoot. The 150-600C is front heavy. Even with the 1.4x TC, the focus in good light is quick. Better than the 150-600 + MC11 combo.
I was mostly shooting honey and carpenter bees in borage and nasturtium. The 100-400 + 1.4x TC did pretty well at this, with a comfortable minimum distance.
Another issue I noted with the a6400 is the SD card inserts into the battery slot, parallel to the open door right next to the hinge. Removing the card is a bit cumbersome for my big XL-sized hands as I cannot get a good grip on the sides of the SD card. Minor point, but would have been easier if they reversed the battery and SD card relative to the hinge.
I'm just starting to look at the photos, so I'll have more feedback later.
What I will do this weekend is some side-by-side tripod shots to compare IQ. I think the 100-400 is better matched against the 500/5.6PF than the Tammy 150-600g2. I'll do some shots at equivalent MP and some at equivalent FL using the d850 + 500/5.6 PF (500mm @ 45 MP and 700mm @ 24 MP) and a6400 + 100-400 (360mm @ 24 MP [500mm equivalent]) and a6400 + 100-400 + 1.4x TC (333mm @ 24 MP [700mm equivalent]). I'll also do some shots at a6400 + 100-400 + 1.4x TC (400mm @ 24 MP [840mm equivalent]) and d850 + 500/5.6 (500mm @ 16 MP [840mm equivalent]) and see how it comes out.