While in the yard for SLEP in Philidelphia I would attend concerts at the Spectrum. The area was just outside the front gate of PNSY. 1983-4 Looks like Freddy changed his custume for this set.
I would sneek a camera and lens into the concert in my socks...and pray they wouldn't pat me down that far. When the concert started I would proceed to the sound and light board in the center of the floor which was elevated. I would use some official looking fake ID to get up on the sound board and shoot away. Never got caught once.