Revolving around a newly developed sensor, the X-T3 features an APS-C-format 26.1MP X-Trans CMOS 4 sensor, which has a back-illuminated design to afford smooth tonal rendering, improved low-light performance, and a low native ISO 160 setting. As an X-Trans sensor, it still utilizes the randomized pixel array, too, which provides a high degree of image quality and sharpness due to the omission of an optical low-pass filter. Versus conventional pixel patterns, the X-Trans design more closely mimics the organic nature of film in order to produce nuanced colors and tonal transitions, while also reducing moiré and aliasing.

The sensor's design also includes an expanded phase-detection autofocus system, which now has an impressive 2,160,000 points that cover nearly the entire sensor area. This AF system delivers faster, more accurate focusing performance along with low-light sensitivity down to EV -3. Complementing the imaging and focusing capabilities, an updated X-Processor 4 is also featured, and delivers faster focus response for subject tracking and also supports Face- and Eye-Detection AF when working in AF-C mode and when recording video.

The X-Processor 4 also utilizes four CPU units for faster image processing and it benefits overall performance with AF speeds as low as 0.06 sec. 0.17 sec shooting intervals, 0.045 sec shutter lag, and a 0.3 sec start-up time. Quick continuous shooting is possible, up to 11 fps with a mechanical shutter or 30 fps with an electronic shutter and a 1.25x crop, and internal UHD 4K60 video recording with 10-bit output is also supported.