Presuming that they have the same APS-C sensor, and then going through the specs of that Sony sensor and then the set of features of the X-T4. Here we go, for the possible new features that had never been offered by Pentax before, in their upcoming new flagship:
- 26MP BSI CMOS sensor (for its high ISO performance, this sample at ISO 10000 may shed some light)
- 18.82 fps maximum frame rate with 12-bit RAW (which will be converted to 8-bit JPEG anyway, limit of the sensor for the read-out bit-depth and rate combinations)
- If 14-bit RAW is implemented (KP and K-1/II have 14-bit RAW), the frame rate for continuous shooting still picture will be in between 6.84 (for highest 16-bit readout of the whole picture) and 18.82 (as mentioned above) - the above brief marketing sheet of the sensor does not mention about the 14-bit readout modes and rates
- 10 fps is possible (considering that the XT-4 offers 15 fps continuous shooting with mechanical shutter, unless Pentax's latest mechanical engineering plus image processing speed are yet not up to there. And, the Pentax has a mirror but the Fuji does not. )
- 425 point on-sensor phase-matching AF in Live View mode, which the X-T4 has
- 10-bit full-frame 4k video in 30p (limit of sensor) or 12-bit 2k video at high frame rates (55 to 111 fps which is the limits of the sensor); Or 10-bit 4k video at 60 fps is possible with the 1.18x crop factor of the centre
- 4:2:0 colour sub-sampling for H.264 codec (which is a bit too much for the dropping of the colour data) and 4:2:2 for H.265 (Pentax may have a different codec and implementation, though)
But since that the K-new will not have any articulated screen / flipped monitor, the video capability of it will not be too strong anyway?
Other sample images of the production X-T4 in DPR's latest full review of the camera can be found here. Also, a quick glance with the comparometer at the DPR, it seems that the ISO performance will be improved from the KP's by one to two stop(s), and which will undoubtedly exceed the IQ of the K-1 II.