I went to Disney last week and wanted to take a picture with my son and the castle at night time ( the castle was full of light bulbs and was really beautiful)
I used 350 D with 50/1.8. I used the Av mode (with the flash on)and autofocus. I tried to focus on my kids and pressed the button halfway and then shift to the castle (so that my kid was placed at the left-handed part of the picture).
But, after repeated attempts, once I shifted to the castle ( I pressed the botton halfway already), the focus re-adjusted again. So all the pictures were failed, clear castle with blurred kids. Finally, I had to change to manual focus.
Is it because the kid is too dark and the castle is so bright, so the focus will automatically re-adjust itself?
Any technique for this kind of photo shoting?