Visible crew/equipment: When Bond and Tiffany speed away from the Tectronics facility, three of the security guards are at their inoperative vehicle, and there's a reflection of film crew on the surface of the vehicle.
Visible crew/equipment: At the Tectronics facility, Bond swipes a quad bike from one of the security guards chasing him. When he reaches Tiffany at the perimeter gate, just as Bond says, "If you see a mad professor in a minibus, just smile," we can see the reflection of the boom pole/mic on the car's windshield, as well as the hood. (01:03:05)
Visible crew/equipment: When Bond climbs off the elevator and hangs for a few seconds, if you look closely at the ground behind Bond, you can see his shadow on the screen behind him, which has the image of the ground projected onto it.
Visible crew/equipment: When Bond and Tiffany are talking while looking at the fish, he suddenly rolls her on her back, saying "I'm on top of the situation". As she turns you can clearly see a plaster (band-aid) carefully placed to cover any...er...accidental revealings.
Visible crew/equipment: When the helicopters are attacking Blofeld's platform, at some points you can see a little black spot moving in the background. It is the radio-controlled helicopter which filmed them from behind.
Visible crew/equipment: When M. Franks enters the customs, you can see the reflection of the crew on the window.
Answer: If you mean by hiding - why is he never seen normally - then it's because he is a recluse and doesn't like to be seen in public (like Howard Hughes was). If you mean by hiding - why was he not seen during the movie - then it's because he was being held captive by Blofeld and his minions. Spectre didn't want him out and about ruining their plans.
Zwn Annwn