Hi Just need to know what form of SD cards can be used once the firmware on my K100D has been installed? I'm looking to buy a Lexar 64GB SDXC card, or if anybody can tell me what the best 64GB card would be to purchase.I don't believe that there is any firmware update that will enable a K100D to use SDXC cards. Nor would I expect such an update to be released.

In other words, don't waste your money on a 64GB card. With the firmware update that IS available for the K100D, the maximum size card is 32GB. Why do you think you need a 64GB card? Your K100D, like my K10D, doesn't do video. On my camera, shooting RAW+JPEG at the highest resolution and quality, I could fit 4,096 images on a 64GB card. My camera accepts SDHC cards, so I could go as large as 32GB, but the biggest I have is 4GB.

I have just got hold of a Pentax K100D, I have checked it's firmware verion which is ver 1. Broadcom Driver Windows 10 Netxtreme 5700. 00. I have found the updte instructions on the Pentax site.

That is far bigger than I ever fill in a single shoot. Cards do go bad occasionally, and they can be lost or stolen. I'd rather not lose several thousand images due to one failed card. Of course, your needs and shooting techniques could be very different than mine.

Its your choice, but I don't believe that 64GB is a choice for you. I'm late to this post, but am trying to update the program on my camera. I have a Pentax K100D and have been trying to follow the directions above for installing and updating Firmware. I currently have version 1.00, and have formatted and copied the required file onto a SanDisk 4GB memory card. The card is now inserted into my camera. However, whenever I turn on my camera while pressing the Menu button I don't get anything saying 'Loading' or 'Updating'. Mine simply tells says: 'Ver: 1.00'.