The spelling is accurate and was taken from a family photograph.
I think you've misspelled it slightly, it's most likely - 'von Tarnowski', there are some hits for that name on the Internet; to make sure, I would suggest you to post a scan of the photo on PF, someone will confirm the correct spelling for you
Any ideas?
I would suggest to lose the 'von' part and search for Aleksander Tarnowski or Tarnawski. I assume you've already searched for Aleksander Taranowski without much luck?