Hi, There are so many cards out there and I'm a bit confused. I shoot mainly photos, but occasional videos. Shoot JPEG Fine/Large. I know it's best to use class 6 or 10, but which brand and type? Thanks for your help. Have a great day. Phil
We don't know which camera body you use but the instruction manual will tell you the brand, size and type of the cards you can use. For example the D3200 Approved memory card table shows cards in class 6 or faster and from 2 GB SD cards to 128 GB SDHC cards and SDXC cards from 48 GB to 64 GB from SanDisk, Toshiba, Panasonic and Lexar. I'm sure there are cards made by other companies that work but these were tested by Nikon when the manual and camera were released.
The D5100 manual pretty much lists the same cards as the D3200. The D5100 is a slightly older body so the manual is lacking a couple of the higher capacity cards but I would expect it would use the same cards as the D3200.
According to Nikon, the largest card the D5100 supports is the 64GB Sandisk Extreme. I've verified that this card works on my D5100. I'm not sure about other 64GB cards. Most people seem to stick to getting a few smaller cards to limit losses from cards getting lost or damaged.