Yep, that's the guy. Nice pic, where did you find it? Please share some of your Dortenmann info.

In my opinion the best source for Luftwaffe colors is the Eagle Editions Luftwaffe Color Chart. Jerry Crandall is a Luftwaffe expert and has contacted the very same company that provided paint to the Luftwaffe in WWII. His chart is created from the actual formulas and comes with a certificate of authenticity from the manufacturer.

To see the chart:
http://members.cox.net/wulfman5/5/Page_41.html