The deserted studio was the old Grand Majestic Studios. The Warren sisters who own it show up in the Bonus Quest and want you to leave.
It is to the far right on Sunrise Street.
To leave the studio, you have to drive back to Sound Stage 1. Then you can walk left to exit through the gate. Once you are in the studio, you can come and go as you like.
Once you are in the studio, just walk left from Sound Stage 1 and the gate to the street will be open to come and go.
You get the camera from the gossip magazine guy, Harvey Scoops, who is standing near the closed studio at the far right of the island (Sunrise Street).
There is no guide. Once you are on the studio lot, you will see the director, Carson Willis, or his assistant Sofia, or both, at the various sound stages.
There are no keys on Back Lot island.
When you are anywhere inside the studio, drive back to Sound Stage 1 and walk left to exit onto Sunrise Street. The gate is now open.
Go into the talent agency. The owner will suggest you meet Harvey Scoops, who is to the far right near the closed studio.
The owner of the Talent Ahency sends you to look for him. He is at the far right, in front of the closed movie studio.
It is on the block to the right of Main Street, along with the movie studio. It is decorative and has huge stone lions out front.
You try to earn some by getting photos for Harvey Scoops, but once you get the film for the camera (from the old guy at the Wax Museum), you fall onto the studio lot instead.
Once you have gone left to the Wax Museum and gotten film for the camera, load it and come back to the studio. Climb the building to the left and use the camera from the balcony.