'Dumb and Dumber To' -- Lights, Stolen Camera, No Action

One of the camera guys for "Dumb and Dumber To" is about to owe the studio a big fat I.O.U. -- cause while he was chowing down at IHOP ... a $500k camera was stolen from his car.

The camera guy was eating something vaguely delicious while the evildoers broke into his whip. Authorities think the crooks may have messed with the door lock.

The camera was reportedly being taken to a waiting helicopter where it was going to be mounted for a "To" shoot.

The photog is offering a $5,000 reward to anyone who can help them find it undamaged.