I am fairly new to the photography world, but enjoying the heck out of it. As such, I am working on getting a better understanding of my Canon 40D. I was snapping pics of my son's hockey game and noticed some differences in the quality of the pics. I snapped 2 pics in a row using the continuous shooting function so I never refocused or took my finger off of the trigger. The first pic was dark like the white balance was off, the second pic was almost perfect. I was using the custom white balance set through using an expodisc. Even throughout the day, sometimes the WB would be fine, other times not.
Here are 2 pics as an example, taken within 10th of a second apart. They have not been modified. I realize that it can be fixed in post production, but wondering why this was happening?