Photography at SX rounds.

It says no video cameras on the supercross site, but it's worth trying:

https://www.supercrosslive.com/faq/#:~:text=However%2C%20in%20order%20to%20maintain,zoom%20lenses)%20are%20NOT%20permitted.

https://www.theanaheimstadium.com/rules/

A phone is technically a camcorder, or a recording device… and lots of people shoot their video content on a dlsr.. it’s confusing. 

Depends on who you get checking bags. I've gotten in with a DSLR some years, and been told no other years. 

Any time I've used a telephoto at Angel Stadium, Feld sends their goons and says to put the camera away or you'll have to leave.