The Sandisk 16 GB SDHC card for my camera (a Canon Rebel XSI) arrived yesterday. I have heard that faster memory cards could improve the number of continuous shots so decided to do some experimenting this morning with the new card and my current slower 8 GB card. Burst mode for this camera is advertised as 3.5 frames/second. However in my experimenting with both cards and using various picture quality settings (RAW down to the lowest quality) I found I would get 2 quick shots and then drop down to about 1 shot per second. Something clearly was not right. On the web I found someone experiencing the same problem had resolved it by resetting their Custom Function settings. I also learned that you can see your current max burst in the view finder (the last number on the right). Before I reset my Custom Function settings my max burst in the view finder was shown as 2, after the reset it jumped to 6 (shooting RAW). Tests after the reset showed burst mode now performed much better. Shooting in RAW I can get 6 shots before the camera slows down. Moving to the highest quality JPG the camera will shoot continuously for 10 seconds+ with no slow down.
Digging a little deeper I discovered the exact custom setting which slows down burst mode: “High ISO speed noise reduct’n”. This article gives a complete description of what this setting and when it should be used: http://www.learn.usa.canon.com/resources/articles/2011/high_iso_noise_reduction_article.shtml. The quick summary is that, if you are shooting RAW (which I do) noise reduction is controlled by your photo software, not by the camera so this mode is not useful. So unless I decide to switch to shooting JPG for sports I’ll be leaving this mode off.
Note that I am not noticing a significant different in burst mode between the Sandisk 8 GB 15MB/s SDHC and the Sandisk 16 GB 30MB/s cards. Testing of the read and writing of files to these cards from a PC show the 16 GB card is about 25% faster. Not sure if that will translate to much of a speed up in my work flow.
After this episode, I have decided to research each of the Custom Function settings and their optimal setting (for me). I’ll post my results here…