Both RAW and JPEG images are sharp, with rich colors, especially at low ISOs. (The ISO range is now 160-12,800, with extended output to ISO 80-51,200). More importantly, I found that nearly all the images I took with the X-T3 were usable -- the the metering system is pretty on point. The handling also comes into play; even with very little time on a new camera, I quickly figured out how to change exposure compensation, shutter speed and other parameters when faced with tricky shots, like the dimly lit tunnel shot below.
High-ISO RAW performance is about the same, or maybe even slightly worse, than on the last model. However, if you consider that the X-T3 has higher resolution, I'd wager that it would perform just as well if you reduce the image size down to the X-T2's 24.1-megapixels.
ISO performance is one of the major ways that a full-frame camera beats an APS-C model. Shooting in similar lighting conditions, I was able to get more usable photos at higher ISO levels on the A7 III than on the X-T3. Even at ISO 6400, a setting that almost always yields pretty clean photos on Sony's model, the X-T3 is noisy in dark areas. I had to shoot the photo below at 6,400 ISO, hoping I could boost the dark areas, but the subjects in the shot are too grainy. On the A7 III, even at higher ISOs, I've no doubt it would've been cleaner.
The problem is compounded by the lack of in-body stabilization, which limits your ability to choose a slower shutter speed to let in more light. That said, I'd place the X-T3's low-light performance equal to, or above, the A6500.
Thanks to the full-sensor readout, 4K video is extremely sharp, and with a high 400 Mbps maximum bit rate and 10-bit video, there's tons of information to work with. You can use All-I recording, which saves every frame and makes editing faster, or Long GOP, which stores key frames and saves the differences between them, for higher quality.
Dynamic range for video is about 12 stops, which is excellent for an APS-C camera but well below the standard set by Sony's A7 III. You can use the F-Log mode to maximize dynamic range, or choose Eterna shooting mode to get a beautiful look right out of the camera.
Rolling shutter, aka the "jello effect," is definitely present on the X-T3, but it's extremely well controlled. That's another check in its favor compared to the A6500, which has some of the worst rolling shutter I've ever seen. It's also not great on the Canon EOS R, despite the fact that it's using an even smaller part of the sensor in 4K than the X-T3.
The video capability blew me away, and the X-T3 should scare Panasonic as much as it does Sony. It has a superior autofocus system to the GH5, and will really tempt folks who want a larger sensor. That said, serious users might still prefer the more professionally-oriented GH5, with its vectorscopes, better HD slow-motion and high-end audio adapters. It's also got a fully articulating screen that makes vlogging much easier. If you're a hybrid shooter who does photos as much as video, though, the X-T3 is a better option.
One thing that remains to be seen is how well Fujifilm's latest model can handle hot conditions and long recording times, given the smaller body that may not dissipate heat well. The GH5 and its video-oriented GH5s sibling have proven themselves to be reliable shooters in most conditions.
The X-T3 has that Fujifilm mystique with a small, pretty body and numerous dials for manual shooting. It performs worlds better than the similar-looking X-T2, however, and might give potential buyers of the more expensive X-H1 pause.
It delivers sharp, rich images with very respectable low-light capability for its class. Thanks to the full-sensor readout, 4K video is tack-sharp, and the X-T3 is the first APS-C camera with 4K 60 fps recording. Should you over- or underexpose video, the 10-bit recording could save your butt. Finally, at Photokina 2018 Fujifilm unveiled three new upcoming lenses to its roadmap, adding to the already excellent glass collection.
Not all is perfect. It lacks in-body stabilization, standard on Panasonic's GH5 and Sony's A7 III and A6500. It's also missing a fully-articulating screen, a must for many vloggers and photographers.
The $1,500 X-T3 is also pretty costly for an APS-C sensor camera, though it falls below the $1,700 X-Pro and $1,900 X-H1 in the X-Series family pecking order. If you're willing to spend another $500, you can get a Sony A7 III or Nikon's incoming Z6, both of which are full-frame mirrorless cameras. Professional video shooters might also want to spend another $200 to get Panasonic's GH5. In terms of APS-C competition, Sony's highly-rated A6500 goes for about $1,100 on Amazon. And if you don't need the extra speed and fancy new video functions, consider Fujifilm's still-excellent X-T2, which can now also be had for $1,100.
The X-T3 is a triumphant return to form for Fujifilm. Even with just a higher-resolution X-trans sensor, vastly better autofocus and incredible shooting speeds, it would still be a winner. But Fujifilm outdid itself on video, vaulting the X-T3 to the top of the APS-C mirrorless podium.