Take a look at my notes which attempt to answer all of the questions and concerns faced when purchasing a memory card for the Nikon D5100. I'll shed some light on compatible memory cards, specific requirements for HD recording, the number of images you can expect to take, estimated movie recording times and other important info.
The D5100 takes 3 types of memory cards…
SD – Up to 4GB worth of images and video.
SDHC – Up to 32GB worth of images and video.
SDXC – Up to 128GB (currently) worth of images and video.
The information below shows the total number of images that can be recorded based on memory card size…
4GB – 422 images (fine) and 171 images (raw)
8GB – 844 images (fine) and 343 images (raw)
16GB – 1,688 images (fine) and 686 images (raw)
32GB – 3,376 images (fine) and 1,372 images (raw)
64GB – 6,752 images (fine) and 2,744 images (raw)
In order to record HD video on the D5100, your memory card will need to have a Class 6 rating or higher. If it doesn’t meet this requirement, video recording may stop unexpectedly.
Each video clip is limited to a maximum 20 minute segment or 4GB worth of data (whichever occurs first). The information below shows the overall recording capabilities based on a movie frame size of 1920×1080, along with the bit rate set to High Quality:
4GB – 28min 26sec (.mov)
8GB – 56min 52sec (.mov)
16GB – 113min 02sec (.mov)
32GB – 226min 04sec (.mov)
If you leave the movie frame size set to 1920×1080 and adjust the bit rate quality to Normal, here’s what you can expect:
4GB – 44min 49sec (.mov)
8GB – 89min 38sec (.mov)
16GB – 178min 16sec (.mov)
32GB – 356min 32sec (.mov)
Speeds & Ratings
Class ratings represent the minimum write speed for a memory card. So a memory card with a class 6 rating will have a minimum write speed of 6 megabytes per second. As mentioned above, Nikon requires a Class 6 rating or higher in order to record and playback HD video with the D5100. I recommend going with a Class 10 card just to be safe.
Speed ratings represent the maximum read/write speeds. If you plan on recording HD video, shooting long bursts of images (10+) in continuous mode or capturing RAW images with your D5100, then I recommend going with a Lexar Professional (133x or higher) or a SanDisk Extreme (30MB/s or higher).
Lexar and SanDisk memory cards are the safest bets when it comes to reliability and performance. I’ve used them for years and trust them with all of my pro work. Recently, I’ve been using Transcend cards for personal use and have been pleasantly surprised. Again, if you plan on utilizing some of the more advanced features on the D5100 (video, RAW, burst) then go with a Lexar Professional (133x or higher) or a SanDisk Extreme (30MB/s or higher). If you just need something for everyday (personal) use, Transcend (class 10) cards are an excellent value.
Here are my memory card picks for the Nikon D5100…
Check out the D5100 homepage for more tips, advice and recommendations. Happy shooting!