Hi:

The 810 CAN NOT use a full size SDHC.

Nokia say's a 810 can use UP TO 8 Gigs. No mention of 16 Gigs. Judging from the past there may be an s/w update when suitable 16 Gig cards are available.

I have yet to see a 16 Gig mini or micro SDHC although I haven't looked for a month or two.

I settled for a 4 Gig micro Class 4. When the time is right, I'll go for the 16 Gig card.

Good luck