I picked up a canon t2i the other day to save some timelapse-related wear and tear from my 7D. It used sd cards, and I quickly realized that some cards are better than others, even when they have the same specs. I was inspired by this post over on peta pixel. This isn’t a very broad test, but I tested all the cards I could scrounge up.
In order to do this, I just popped in an sd card and fired off 15 shots. The quick cards bogged down significantly less than the slow cards. You can see the in-camera buffer get filled up after 7 shots, and then the real test begins. The gap between shots is now due to the write speed of the card. The end of the green bars represents the total amount of time that the card spent writing buffered data. Since I didn’t line them all up starting at zero the numbers to the right of the green bar represent the total time to shoot 15 shots.
What does this mean? Well, it shows the comparative speed of different cards I have available to me. I wouldn’t even think of using the slower smaller cards for video, but this certainly puts some data behind that feeling. For stills the speed really doesnt effect me very much, but it is crucial for video. If I am shooting hd with a high iso (lots of detail make a hard to compress image) then I absolutely need to have a fast card. This way I can test my cards (in combination with my camera) to see how well they perform. I am also interested in testing out different priced cards in the same class to see what the return is for price paid. Lastly, it brings up the interesting idea that a slow enough card can almost replace an intervalometer. My super old sandisk 1Gig card took almost 3 seconds between shots! That could make for an acceptable time lapse interval in a pinch.
Note – I know that there are much more precise ways you can actually test cards using a computer. I don’t want that. I wanted to test both my camera and sd cards simultaneously.