3D production can be such an anomaly. Every system is different and everyone has their own opinion about 3D and what they think is best or "right." But one thing is for certain, it is nice knowing the technology BEFORE you have to go in as an operator, AC, or even DP. So per several people's request from the SOC, Society of Camera Operators, I put on a one day intensive class with Jill Smolin at 3Ality to help clear up any confusion with 3D and get to the bottom of what is exactly going on in that dark booth back there!
Even though the 3Ality rigs are what we call the "Ferrari" of rigs, it is a great place to learn the basics of 3D. Because the system is completely motorized, (i.e. alignments, convergence, interaxial is all motorized) it is easy to show quickly the effects of 3D decisions made on set and how framing and blocking can either help or hurt the overall imagery.
Rather than me going into depth the explanations of 3D in this blog (since that information can easily be found online such as the Stereo Sisters website where their resource tab can provide you with a lot of 3D information), I would much rather discuss the 3D politics and the basic workings of what happens on set.
First off, the list of crew for a typical 3D film. And when I say "typical", I am describing a set from a 3Ality show such as Step Up Revolution, or Dawn of the Planet of the Apes.
Director of Photography: Does everything a DP would normally do, lens choice, lighting, blocking, etc. But takes on an additional challenge of working with the stereographer to define the overall depth for each shot and how that progresses and changes per scene and throughout the film. Sometimes the DP doesn't deal with the stereographer at all, sometimes he/she chooses to be heavily involved. It all depends on the show.
Stereographer: The head of the 3D department. The engineers and rig techs work under the stereographer insuring that the functionality of the 3D rigs are working properly so that he/she can change interaxial and convergence without the system going out of alignment. The stereographer is responsible for the depth budget of the film and making sure that the 3D will be comfortable for viewers in the theater.
3D Engineer: The is the person behind the curtain working the the alignment software doing the motorized alignments of the rig for every lens change. They are in constant communication with the rig tech who is on set next to the rig itself communicating anything they see that needs to be fixed. This could be rotation issues, dust on the mirror, edge violations in frame, flares, etc. The engineer is the stereographer's right hand person making sure the images are good before rolling.
3D Rig Tech: This crew member is the one physically handling the rig. They re-position the rig from head to head, change the lenses with the 1st AC, manually handle rotation and any other rig issues that may come up. They are essentially another "AC" if you will, but handling the 3D aspects only.
Now this is where the confusion comes along. All of these positions, besides the DP, now have to infiltrate the camera department which is used to having only three to four positions, the operator, 1st & 2nd AC, and DIT. How do these positions work together? How do they hurt or help each other? And the answers here can vary from set to set. Like a normal 2D film, there are a variety of ways that a DP will communicate with their operators and ACs. And the same goes for a 3D production. But the main thing that I feel lacks in many 3D productions is that not everyone has learned the essential basics of 3D and why their decisions affect everyone one set. Here are a couple of examples not necessarily from any particular film I've worked on, these are just general issues.
1. The DP is lighting while the camera operator is finalizing the blocking with the director and actors. They go from a nice wide shot to the actor walking into a medium shot with a tree in very close foreground left of the frame. In a 2D composition, this would not pose any issues. However, the DP and stereographer discussed having very deep stereo for this scene so the stereographer has set their interaxial to a wide IA. (To learn more about IA, convergence, and other basics, click here). They also set the convergence so that the actor would come just a little negative giving him an ominous feel to the audience. But wham, this tree is now close foreground causing an edge violation and a very uncomfortable one at that with the wide IA. Therefore, two things can happen. The camera operator can re-block the frame to not include the tree, or the stereographer can push the actor into positive space with the tree right at screen plane. This is where having everyone in sync of the overall 3D imagery can really help production. If the operator knew the lingo ahead of time, and the DP and stereographer said to him/ her, "Just make sure at the end of the frame, the actor can come into negative space," then they would have known to not frame the tree into the foreground. This is just one of many examples where an operator can help with blocking a scene to make for better 3D imagery, therefore creating a truly dynamic 3D shot instead of a compromised frame.
2. A DP understanding focal lengths that work well in 3D is also incredibly important. For the most part, to maintain the integrity of a 3D shot, you generally do not want to go longer than a 40mm lens! I know this sounds absurd to many DPs who love that long lens look with the depth of field falling off. But one must understand, that when you start going into longer lenses, you basically aren't shooting 3D anymore. Everything becomes compressed and flattened which defeats the purpose of shooting 3D. Not to say don't do it. It's just an understanding of what you are creating in 3D space. But I also learned in our 3D class from Stereographer Paul Taylor, who attended our SOC class, that a long lens can work great on an extreme closeup on small objects provided you have a very close background that won't diverge. But these are all decisions that should be made based on a clear understanding of the geometry and physics of 3D.
3. An AC's understanding of 3D is critical to the speed of production. Most importantly, understanding the communication that happens between the rig tech and engineer and how this can affect their protocol on set. The thing with 3D filmmaking is that it can move like clockwork. But sometimes it doesn't and there is an order in which alignment happens, FIZ handsets are calibrated, etc. I won't go into the details here, but the best thing that the 1st and 2nd AC can do is literally do a practice run with the engineer and rig tech for lens changes and other camera functions on set and figure out their system of communication that will serve them best. Don't figure it out on set! Use prep time to do a practice run or take a class! Also decide with the operator what some priorities could be. There have been times where the DP needed to simply see the lens size in the camera and see the move on the technocrane to know if it was the right lens size. This can be something where everyone is in agreement prior to production that when this happens, alignment is not needed right off the bat. Put the lens on one camera, give the DP that eye only to view, and let them quickly block out the move with the lens. If they like the lens, then they know that now the other lens will be added, an alignment will happen, and then they are free to block at will. Where the problem with this happens is they all of a sudden say, "Ok, great! Let's shoot it!" And the other lens has not been added to the other camera yet. So, this is where your 1st AC can help by communicating with the operator and DP that the camera team will need a couple of minutes to add the second lens and get an alignment done. And truthfully, a prime lens change if all the lenses are physically the same size, which many times they are, from the lens change call out to a complete alignment, this can happen as quickly as 4-5 minutes.
One thing that I love about 3Ality is that they are very open about the education of 3D and using their rigs. They understand that the more crew and production members understand what is happening with 3D, the better the project will be and the overall visual experience will be in the theater. When you have everyone working seamlessly together, it shows on the screen. So if anything, what I want you to take from this blog is that if you know you are going to work on a 3D production, try to learn 3D basics before going in! And if you can, be there at prep, go through an alignment and lens change run through with your techs, and try to iron out protocol before your first day of production. And even if you don't like watching 3D movies yourself, understand that your kids do and the other half of the world does too and you are responsible for their movie watching experience.