I wanted to do a timelapse video with more than one photo per second. Since the shortest interval available in interval timer shooting on the Nikon D7000 is one second, I decided to simply set the camera to continuous low (CL) shooting mode and keep the shutter button pressed with the help of MC-DC2 remote release cord.
I started by setting CL mode shooting speed to 2 fps. To my surprise, the camera kept the rhythm for the first eighteen photos, and then started to lag. Here's the audio recording of the shutter:
The first nine seconds, the camera continues to shot two photos per second, but later, starts pausing at regular intervals every two photos.
Usually, this means that the SD card is too slow, and the buffer of the camera fills up.
However, I'm using an SD card which is expected to be fast enough to record the 22 MB .NEF files. The camera is set to record to the first slot only. The card is this one:
which should give 50-55 MB/s write throughput, which means enough time to store 44 MB corresponding to two files. Testing the card speed from a PC with an old reader connected through USB 2 was inconclusive, since it gives the average write speed of 24 MB/s (which makes no sense given the results obtained with the camera).
What is happening here?