3D Imax and D-Cinema 3D
3D IMAX and D-Cinema 3D have different aspect ratios, D-Cinema 1.78 and Imax 1.33. In order to capture both formats in one camera the default Aspect ratio “should” be 1.33 so that in post you have vertical frame adjustment for D-Cinema.
There are presently at least 4 Imax Movies using Si 2K 3D as second camera application. The same holds true for S-35 mm full aperture 3D systems. The specific applications are size / scale driven.
The primary rule to properly re-purpose to for Imax is to utilize the full IMAX negative for large volume wide establishing shots and use the smaller formats as the camera moves closer to the finer details of the subject. The larger scale of IMAX image holds the details in vistas and S 35 mm format medium shots and 2K Digital capture can work closely and quickly in close ups and action shots.?The advantage to using multiple formats is getting the equipment into places where the larger format cannot be. The disadvantage is management of work flow both in capture and mostly in post. The editor ends up with the same net image size but the file management is convoluted.
Personally I can well see the differences in formats mixed on the IMAX screen – obvious to trained eyes and not so obvious to general public. However the quality of experience for many people is enhanced when the ‘feel’ more detail subliminally rather than point to it on the screen. This is why in a documentary dealing with vast Geographic space may demand the use of full Large Format 15 Perf 65 mm Imax format negative for many shots. This is a stark budget concern.
I have shot Shrimp farming Aphides (Volcanoes of the Deep Sea) at the hot vents of the mid Pacific ridge at 4,000 meters of sea water in manned submersibles using macro HD format. It was the only tool available to reach out from the internally mounted IMAX cameras to the tiny shrimp 4 meters away from the sub. The fact that we filled the IMAX frame with the body of a 5 cm long shrimp created the detail volume that mimics IMAX format itself.?In summary I can say that you can get away with just S 35 mm negative and 2K Digital RAW but in the end, the subject will suffer from wanting 15/65 mm negative.
The other factor you must be aware of is presentations running time. Unless this is a one minute trailer for IMAX theaters, the movie must conform to the IMAX 45- 50 minute format for Large Format Science and theme park venues or the full 90 minute + feature drama block buster length. They may not show other running times because of schedule (projector re-loading disruptions). I know that 10 -15 minute format short films have been flatly refused by IMAX in the past for this reason. The IMAX 4K projectors may have different server arrangements to accommodate odd running times. I don’t know their present policy so you will need to contact the specific theaters in question or IMAX Ltd. for details on tolerable running times.
Most Digital Cinema 3D theaters have a different screen to audience scaling from Imax. The D-cinema is a slightly weaker experience because of the distance to screen and magnification ratio. People always complain to me that they did not enjoy D-cinema movies that they could compare directly with the same 3D movie in IMAX. There is less parallax generated in the D- cinema so you need to create more aggressive 3D in original capture. The IMAX theater positions the audience very close to the screen so there is more parallax (3D effect) because their eyes are positioned in closer proximity than in the D-Cinema .This needs to be dealt with in capture by being cognoscente of what will be too aggressive in IMAX and not “3D enough” in D-Cinema. It takes a bit of experience to know when to hold the horses’ reins in or let it gallop into the theater!
By William Reeve csc