Hi, welcome to the Magix forums.

First, you will see I have changed the Product heading for your question. You posted it to the Photo and Graphic Designer area but your question is clearly about Photostory, or Fotostory as the Forum heading lists it!

If by size you mean the physical size of the images you wish to use if those images were printed on paper, there is really no limitation of size. Any image you place on the timeline will automatically be displayed by Photostory at whatever "size" your choice of screen aspect ratio allows. If you choose a 16:9 or a 4:3 display ratio, your images will be best fitted by the software to the available screen size. The actual physical dimensions of any "printed" version are entirely irrelevant. So, some photos may be displayed with black bars either above and below or both sides of an image if it does not have the same aspect ratio as your project.

HTH

Jeff
Forum Moderator