Such a great forum, this is my first post...

My bonsai maple is showing spots on the leaves. I have had a look on google to see what it could possibly be, and the most I have found is that it could be a fungus. Still not sure.
Has anyone else experienced this and how have you overcome it? (geez that sounds like a job interview question! lol!)
Thanks in advance for the help x
PS : have attached a pic... hope it came through.