Thanks for your quick answer. I appreciate your willingness to help :-)
I now purchased the Photographer theme, which looks pretty nice and clean indeed. Unfortunately, the size of the images in the slideshow does not appear any larger than in the former theme (see http://ilcimento.wordpress.com/2013/07/25/the-tokyo-post/), and is definitely smaller than what the full-width layout of the new theme would allow. If only the dark gray window in which the slideshow finds place could be made higher, the images (which are uploaded way wider than they appear) could be shown with a more decent width, without any jumping around as the image changes. It's obviously the height there is unnecessary limitations with.
Furthermore, the new theme has some not so funny bug: when I select a header image (no matter how small) and apply it, it makes the title disappear as if header image and title text were given the same place in the page layout.
For a photographer the possibility to show his photos in a way that lets viewer appreciate them is crucial. And I'm so frustrated by these tiny images that am considering finding another blog engine or some CSS genius that can fix things for me that way (though mine are so simple wishes that the most basic layout editors should let me take care of them). Anyway, thanks so far.