Originally Posted by Ken Ross
This is a next gen processor and it's discussed in the Sony literature on the new camera. I think they need better heat sinks and that probably requires a bigger body. It's absurd that after all this time they refuse to redesign the body to be slightly bigger so as to better dispel the heat. In fact this probably could have been done with the prior processor. I don't think any user would be so turned off by a slightly bigger body that it would drive them to a different company's cameras.
No, it is not a next gen processor, it is the same one as the a7III and a6400. If you read their press release carefully you should notice that the processor is described as "latest generation" in the overview points, but is not mentioned again at all in the more detailed descriptions of the new tech in the camera. The talk about all the other new components and tech in the camera, but say nothing about the processor. That means it is the same processor as used in the cameras from the last year or so. The processor capability (as measured by the oversampling of a direct readout image, which is 2.4x on the mark IV compared to 1.8x on the mark III) is exactly the same as the a6400 (as well as more recent older cameras). They do not have a new processor in this camera, so it is no surprise that it's video capabilities are similar to recent Sony models.
As for heat dissipation, it does have a larger body than the mark III, especially the grip which is much deeper. But, the mark IV has to work 33% harder to process the same image as the mark III due to the extra pixels that need to be handled, so you are not getting any net extra cooling.
Remember, this is primarily a high pixel specialist stills camera, which can shoot decent video as a secondary function. The video centric version of the a7 is the S camera, and that still has to arrive. That will have a lot fewer pixels it has to process, which means that something like 4k60 is realistic. It may even introduce the real next gen processor, since that is the camera type that really needs it. Waiting for the new processor may well be the reason why the a7SIII was delayed for so long.
One thing this camera will do is put some pretty impressive AF capabilities in the R line and bring it well before the mark III in this respect. Not to mention what sounds like a very nice viewfinder.