To provide photographers with a broader perspective about mobiles, lenses and cameras, here are links to articles, reviews, and analyses of photographic equipment produced by DxOMark, renown websites, magazines or blogs.
The Sony a9 is the Japanese manufacturer’s latest flagship mirrorless offering, boasting a raft of high-performance features for action photographers. The 24.2Mp stacked CMOS sensor offers up to 20x faster sensor readout times, with an electronic shutter capable of impressively quick 1/32,000-second shutter speed, and blackout-free continuous shooting.
The Sony FE 100mm F2.8 STF GM OSS is a short-telephoto prime for Sony full-frame mirrorless E-mount cameras such as the high-end a9 and the earlier A7 models. Besides being a G-Master model with high-grade optics and build, it has number of interesting features that make it stand out as a highly specialized lens for portraiture. First is the inclusion of optical image stabilization, which can be used to complement the camera’s sensor-shift stabilization (where applicable); and second is the use of an apodization filter or APD element as part of the optical construction.
The Sony FE 85mm F1.8 is a high-speed standard prime for Sony full-frame E-mount cameras such as the A9 and A7 cameras, but will also fit smaller “cropped” sensor APS-C models such as the A5000, on which it offers an equivalent field of view of a 130mm focal length.
Well, There are always trade offs with anything in life. A9 does well at some, and has some advantages for sure based off specs and the reviews I've seen, but comparing dynamic range they all meet around 640 and D4s is only slightly lower past that point against A9. They are basically the same from 100 to 640(D4s and A9). I dunno, their new lenses and newer tech or interesting for sure, just not sure if this is the right system to jump yet. With the other comment about compressed at 20 vs. 12. But you get much more out of the points being edge to edge, especially on the D750 which is so small its pitiful.
IQ wasn't the most important factor when designing this sensor and the score shows it. It's a a7 II sensor (which was also in the A7 and is in The Nikon D6xx and D750 where it performs better), on steroids, resulting 2 points advantage scored because high iso performance improved at the cost of DR and colour depth a bit. For that a new stacked design was necessary. Speed comes at a price it seems. Both in $ as in IQ.
I think its very important to sports photographers that these 2 image qualities be compared. 1 lets you shoot at 20fps and the other at 12. If you are shooting at 12 the A9's advantage over the 1dx mk2 and d5 is gone. I am a 1Dx mk2 owner and if shooting Compressed Raw at 20 fps causes me to take a lower quality picture then the extra 6fps is a downgrade to me.
I did head to head testing with the a9, a7R 2 and 1Dx mk2 and these results fall in line with what my eyes saw. A9 very slightly less noise in blacks than a7R 2 however the sony cameras were very noticably brighter from iso 100 to 3200 than the 1Dx mk2. Could have been their lenses though but I think thats part of the advantage to the system. Lower Tstop on the sony lenses.
Thanks to DXO for fast completion of this study. Because this is the first 24 mp ff BSI sensor, this test is particularly important. Maybe the most important clause in this entire article is: "but the real story is the a9’s rise in dynamic range at mid to high ISOs. From ISO 1600, both the a9 and A7R II pull away from the A7 II, with excellent dynamic range over 10EV possible on these sensors up to ISO 6400". See also the similar clause relating to color. The calculated ratings based on low ISO, (translate lots of light outdoor shooting)don't really tell the story. Nearly every camera does well in those conditions. Likewise, the possibility of recovering some kind of compromised image at high ISO's does not address every day photography. What really tells the story is is IQ from 800 to 6400 ISO. Next, the lenses. It seems predictable that the lenses that score high pmp's with the A7rII will do even better with the A9. But getting confirming measurements from the lens tests are going to be important for many of those thinking of spending $4500 for a camera.