That's news to me. Gotta be the first gp not allowing you to take long lenses. I've been to loads and they all allowed me to take my 100-400Firstly no selfie sticks but I suspect you aren't interested in that. Also no large camera stands. There is restrictions on large lenses especially the sort that a media pro would be using. You should be able to find details @ www.singaporegp.sg under Circuit Access on what spectators can and can't take into the circuit. My sister did note that she didn't see any spectators with large lenses at last year's meeting, but that could have been down to the area of track she was viewing from.
So you can bring and use them. Just not in the grand stands. That's fineFrom the Singapore F1 site:
PHOTOGRAPHY
With its stunning backdrop of downtown Singapore, the Marina Bay Street Circuit is a photographer’s paradise. There are plenty of locations where you can find that perfect shot – go out and explore the Circuit Park!
All equipment brought into the Circuit Park should only be for personal use and not for commercial purposes.
To avoid hindering patrons' view of the race and to ensure an enjoyable experience for everyone, please refrain from using the following items at Grandstands, Viewing Platforms and the Padang Stage fanzone:
Tripods
Monopods
Cameras with telephoto lenses
http://www.singaporegp.sg/eventguide