If you plan to take the upgrade exam from 6 or earlier, make sure you read the appendix. There's a lot of stuff (from OCA 8 and OCP 7) that are required knowledge for the upgrade exam and not in the OCP 8 objective list.
Gian Franco wrote:In an attempt to polish an old certification (SCJP5) certifying for SE 8 this year is in my radar ;)
Were does the focus lie nowadays when it comes to this certification?
So you need the "Upgrade to Java SE 8 OCP ( Java SE 6 and all prior versions)" exam (1Z0-813). Here you'll find all exam topics you need to know to pass this exam.
Besides the new Java 8 features (streams, lambda expressions, interfaces with default and static methods, Date/Time API) you also need to learn about new Java 7 features (diamond, multi-catch, try-with-resources, NIO.2). Probably the best you can do is purchase an OCPJP7 study guide and use it in your preparation to study the Java 7 related exam objectives.