I just popped a Transcend Ultimate C10 card in my 150 and I get an error message that I have to change my recording mode from PH1080i. I tried to format the card and start over, but got the same message. Does the 150 only accept C6 and below?
When the HMC150 was introduced, there was no such thing as Class 10. SDHC cards came in Class 2, Class 4, and Class 6. So when they introduced Class 10 cards, the HMC150 didn't know what to do with it. The Panasonic engineers rewrote the programming code to understand Class 10 and issued a firmware update. Go to the link above and update the software in your camera and it will be able to work with Class 10 cards now.