Hung out in basically same place all day, catching riders from 6-20 feet away. Nice tight corner, might have been better with wide angle, but seemed to do okay with lens at about 100-135 mm focal length (using 70-200 F4L). A fellow I met at at Crystal City, also working with Canon 5D, used his ISO and shutter speed cranked way up (e.g., ISO 1600+ w/1/3200 shutter), so I tried amping these settings a bit. Basically, I didn't like the results. High ISO resulted in loss of fine-grained detail, and increased depth of field so much that backgrounds came into focus and proved distracting. (In many shots, you can see my friends chillin' in lawn chairs under their canopy or other noise, like building roof antennae and telephone wires.) Lesson learned.
During my only saunter of the day, a junior crashed after high-speed corner following downhill chute. Fearing it was my own (I asked, "red and white?" and the official said "yes," making it likely one of the kids I work with ...), I ran to the crash. It was a high octane junior from another team. An EMT was on scene, so I put on blue gloves and took C-spine (held his head to immobilize the patient's cervical spine). The youth's helmet had been blown apart on the left side, so we feared head injury; 6-8 cm laceration on left face, possible jaw/orbital injury. Hip abrasion and injury. Transferred C-spine to crew when ambulance arrived. I've seen a lot of injury, but this one made me nauseous. Maybe because it was a youth like my own, or empty stomach.