An initial impression review with the caveat that I only shot for 4hrs and took 3100 shots....
I shot all birds. I shot in locations that I've been shooting at all year with A9II, A7RIV and R5.
I had full sun for all my shooting starting at sunrise with golden light and progressing to mid-day harsh light...keep that in mind....
* IQ and colors of the low ISO files are up there with the best I've seen...and I've seen a lot (ie A7RIV, D850, Z7, 5DSR etc). High ISO is TBD.
* AF hit rate with the 600GM, 600GM/1.4TC, 200-600 was as good and could be even better than the A9II.
* AF results with 600/2x and 200-600/1.4x were affected by heat haze over the water and over sandbar. I only used those later in the day as they weren't my primary goal to test on first outing. I will test them in better light and in more stable conditions as soon as I can
* Power-on time is way improved. You can actually flip the power switch as you raise the camera to your eye and EVF is active by the time you look in and AF works.
* Power from sleep is also very quick...I don't think it is much quicker than power on. Both are as fast as you need now.
* EVF wake when you don't let it sleep (note EVF still goes off when sensor is inactive) is really quick.
* Things like hitting a Recall Custom Hold key or Recall Reg AF Area Hold key are snappy now. Lag of display is gone.
* Battery life seems worse than I'm used to but I was going a little crazy today so I'll confirm that later. I was into my 2nd battery after the first 3 hrs.
* BEAF is way better than I thought it was going to be after reading/watching some of the initial reviews like T&C. But I was expecting it to be better than T&C said because other short clips (like the bee-eater clip) showed it very responsive.
* BEAF is on par with the R5. However, there was one species I found where the A1 sort of sucks and only occasionally recognized...that was a Black Oystercatcher. The R5 is perfect on Black Oystercatchers.
I need to test on a lot more species. Female Goldeneyes was much better than male Goldeneyes. But both did work.
*BEAF seems to not just be looking for a "Dot". It is recognizing the shape of the bird and then recognizing the eye. Although it isn't like the R5 which shows square/rectangle on the entire bird, then the head and then the eye. A1 does sometimes show a larger square on the bird but mostly just jumps between dancing dots and small eye square or RTT icon and small eye square.
*Once BEAF recognizes a good shape to the bird and finds the eye it can keep recognizing the eye even when the bird goes into weird positions (think odd preening poses that ducks do). But if you try to have it find the eye starting off with the bird in some weird position it usually won't see the eye until the bird is in a more upright and side profile silhouette.
*The first time I used the R5's BEAF I used it on some Yellowlegs doing their erratic foraging while spinning and dunking their heads. The R5 blew my socks off as it could switch onto the eye even as just half the eye came back out of the water. Well the A1 using Dunlin as a stand-in (not quite as twirly and erratic as YL but still head dipping and turning) did equally as well. Coming back onto the eye as soon as the eye was back out of the water.
*BEAF is good at distance....just like the R5 it is amazing how small a bird can be in the frame and it just locks onto the eye. So far that the shot would be crappy.
*BEAF did activate on BIF quite regularly if I did my part and kept the bird in frame with a smooth panning technique. (this included Bufflheads, Mallards, Wigeons, gulls and an eagle). More erratic (ie poor) panning technique did not present the AF sensors with a stable enough image to activate Eye-AF. About the same as on the R5. Technique is critical for BEAF for BIF. Of course I was using Zone a lot of the time and in Zone if I don't keep the Zone on the bird BEAF doesn't work. I will try some more with Wide today and see if I can be a little more sloppy and still have BEAF activate.
*On the R5 if you switch into crop mode it often will find an eye that it wasn't finding in FF mode. I need to test to see if the A1 is similar. I'm not sure yet?
Things I need to investigate further:
* Reading the manual and the DPR review I was under the impression that shooting H+ (30FPS) (making sure one is in Lossy Compressed RAW) that the eye point would back out to 0.7x from 0.9x. Mine wasn't backing out. It only backed out if I set Finder Frame Rate to Higher (240hz) as expected in that mode. I'm confused with this? Did others see the EVF back out when in H+ and RAW set to Lossy Compressed??