Sorry, but I discovered another wrong behavior concerning this topic.
I modified the image.php a little. Instead of using the function getProtectedImageURL() to show up the image, I did include getAlbumLinkURL() to go back to the album/subalbum. But the link generated by getAlbumLinkURL() leads not back to the related subalbum. In case of the above mentioned example the link to the subalbum looks like this: http://www.synnatschke.com/gallery/north-america/usa/arizona/misc/page/2
The correct one should be this: http://www.synnatschke.com/gallery/north-america/usa/arizona/misc/