choppy video

I was doing some test footage tonight on my a57. I was in the kitchen which is fairly well lit and I popped down the frame rate to 24 so I could bump up shutter speed from 1/125 to 1/50. This was my first time taking the camera into 24fps mode but bottom line is the video is choppy when I pan slowly side to side. All manual settings, and manual focus. I am using a class 6 card so I dont know if that is the cause or what. Any idea what it may be?