Ultra is a type of render, it doesn't have anything to do with image dimensions. It has to do with the features that are at work during the render, how many passes, etc. So it will probably add a bit to the time the render takes, but the dimensions of the image are whatever you've chosen in the upper-right of the render options for that scene. As for why your Vue 4 won't render to disk properly, well you're not imagining things. Several folks are reporting that problem (just ask Bloodsong!) and so far we haven't found any related reasons for it. It's just that for some, Vue 4 doesn't seem to understand how to complete a render to disk properly. It's one of the things that needs fixing. :/ And yes, you should be able to use any of the render types to disk as well as to screen. I used Preview mode on the above image.