The GP-Camera
The GP-Camera is a rack-over Mitchell Standard which has had a number of modifications to make it useful for shooting VFX.
All
Mitchells (unless in a museum!) have been modified pretty extensively
over the years. When we got this camera it had not
been used for ten years since it was on the film "Event
Horizon". On that film it had been used with a BNCR mount
replacing the original turret and a large stepper motor standing in for the original motor.I rebuilt the camera with a new front plate and PL-Mount. I also fitted a large servo motor to replace the stepper motor.
The reason for building this camera was initially to overcome a specific problem when shooting time-lapse footage. The problem that we had was that a system like the internal capping shutter and single frame hand controller on the 435 took 2 seconds to reset between frames. This can give a "staccato effect" to time-lapse footage and we wanted to reduce the "shutter closed" time to a minimum.
The GP-Cam can pull-down in 1/50 second thus giving an effective 360 degree shutter for slower frame rates.
You can clearly see the difference between this shot with one frame taking 8 seconds with a 180 degree shutter.
8sec 180deg Shutter
and this one taking 8 seconds per frame with the fast pull-down 1/50 sec ..
8sec 360deg Shutter
Some apple computers have a problem with this type of mpeg so I have uploaded them to my Youtube page.
Just before Christmas I was asked if the GP camera could do 5 frames per second with the fast pull-down .. I was massively dubious but very wrong the camera will do 8 fps with the 1/50 second pull-down (I dared not go any faster!). The result of those tests was the Acela commercial .. this is shooting at 6.25 fps with 1/50th second pull-down and then slowing the footage down with chronos.
Acela Commercial
The GP camera will either run as a stand alone camera with a remote control to do "360 cam" or it can be used with Kuper for effects .. We recently did a test where we ran the camera at 25fps then ramped with the shutter closed down to 1fps 360degree shutter (while the shutter was dark the kuper rig also pulled the stop down) then zoomed in then ramped back to 25 fps .. this looked seamless on the film.
It's possible to ramp the rig and the camera together if the GP camera is under Kuper control it's also
possible to put "Virtual shutters" onto the camera for use with motion control.The timelapse on this commercial was shot using the KT rig with the slider as a lift and the GP-Cam running at 1 fps. Note this is a real kitchen not a studio.
Food Standards agency
Be aware that because the camera is rack-over you can EITHER look through the viewfinder and see video OR you can shoot film, whilst the film is being shot you cannot see the image being shot through the viewfinder ..
© Justin Pentecost, 2013.