This section covers the simplest questions usually associated with Video Assist
- Why I need a VA rig at all?
You may not. It depends on the size of the project, the style of the movie, and the working style of the Director. In short, while VA is usually an extra department, two extra people and a truckload of equipment, it is almost impossible to shoot todays production without it. Generally it not only gives an instant visual confirmation to the Director, it helps continuity to extent, makes costume and props life easier, helps to eliminate costly mistakes with VFX shoots, gives some possibility to check focus, and speeds your production up in several other ways.
- Aren’t a monitor and a cable enough?
That is again your call. A monitor connected to the camera will give you a live picture, and that helps a lot of departments, but is nowhere near a full video package. Obviously, without recording the feed, there is no way to check focus, composition and continuity after the shot. A simple monitor may work in commercials and documentaries, but a feature film or a complex commercial needs much more.
- Why can’t the Assistant Camera do this job?
Ask him/her. If he takes this new responsibility and will do the job, its his call, but sooner or later he will find himself working for two bosses. The 2nd AC is very close to the 1st AC, and he will want to stand close to the camera to be ready with everything, and only keeping half an eye on the monitors. Pretty soon the Director or Script Supervisor will grew tired of calling him back to the monitors to do playback, and will control the recorders on their own, or, more likely, demand a person who has no such split responsibility. My experience is that while VA and AC guys help out each other frequently, one man cannot do both jobs except on the most trivial shoots.
- The picture on the monitor is very bad. Is this how it will look at the screening?
No, there is no need to worry. If you are working with film cameras, the image you see is captured by a miniature video camera built into the viewfinder piece on the camera. The image quality of this video camera was compromised to keep the real image (the one going to the film) as good as possible. While todays cameras have much better video assist systems (especially the Arri 435ES, 235, and Arricam systems), the picture will always look worse on the video monitor. The CCD video chip has a much smaller dynamic range than film, so whites will be blown out much more easily, and dark areas will be darker. Special lights not set for daylight or tungsten white balance can throw off the colors of the CCD. When using a higher sensitivity stock, the video image has to be gained up, and will have much more noise than the film will.
When using a HD camera, you can either watch a HD picture directly from camera, or a downconverted SD image. Both of them are much better than film video taps, most HD cameras will give you the almost exact picture you will see later in broadcast. This means that with a properly set and configured HD monitor, and unlike with film, you will see what you get.
- My (film) VA picture is not sharp. Is there a problem?
The video assist chip inside the camera has its own focus adjustment. If your whole image looks blurred (including the viewfinder marks), the AC should be able to make it better. For this very reason, focus should never be checked with 100% certainty on a video screen with film cameras.
- My picture is very dark/bright. Is that normal?
Most probably not. The video chip in the camera has its own iris/gain setting. If set incorrectly, it can cause the image to be very bright or dark. Setting the iris or gain (opening/closing the tap) would help the problem. But be aware, some situations are calling for a seemingly incorrect setting! When the camera is on a Steadicam, the Steadi operator sees the same picture as you do. He has priority about how to set the iris – he may need to make the image dark, in order to see the lights on the edge of the frame for example. Same goes for crane operators. Also, when the camera is running off-speed (like 36 or 48 frames per second), the iris will be opened to compensate – the image will darken when the camera runs. This will cause an incorrect image when rehearsing, but it will be okay in the take.
- My image is flickering. Is that normal?
Most probably yes. Basically, a video tap runs at 30 (NTSC) or 25 (PAL) fps, and the film camera runs 24, 36, 48 or similar speeds. While 24 fps this is usually corrected, but in higher speeds most cameras has noticeable flickering. Newer ARRIs and Arricams have a framestore built in, which compensates the flickering, but older cameras will be flicker no matter what you do.
- Why do I need a tape recorder for every camera if we also have an expensive hard disk recorder?
The tape recorder (usually a unit called clamshell, a DV or D8 recorder) is there for archiving and backup. Todays computers and HDDs are fairly stable, but without tape recorders you simply risk loosing every one of the VA recordings, and that’s a big problem, especially on a long feature film. Also, tape machines are very reliable when treated well, so with getting a dual system you can be sure that every take gets recorded. On commercials and stuff you can get away with a HDD only, but features calls for backup. Also, sooner or later the hard drives will fill up, and they need to be formatted. From that point, only tape remains. On a long movie we usually format every 2-5 weeks, depending on the system used.
- Why is a hard drive system better?
Basically, HDD recorders are much quicker. Playback can be near instant, like 3 seconds after the cut you can be watching it back already. Tape can take a few seconds more, which is not much, but can add up by the end of the day. Also with HDD, recordings from the previous week, or even 3 weeks before can be called up in a matter of seconds (depending on when the drive was cleared last time). This can be a significant time saver. Switching from live to playback is also faster with HDD.
HDD recorders can "simulate" slow-mo. You can watch playback at 36 fps, and it will look similarly on how the shot will once developed.
Some HDD recorders also give you the ability to do a rough edit right there on the set. While this will never suppress the need for real editing, matching of angles and shots can be verified quickly.
- What is an on-set editor?
On-set editing usually takes the VA footage, and does a rough edit shortly after the shoot was done. This usually means right there "on-set" - hence the name. This can be done with most HDD recorders, and by your VA operator, but you can also ask a separate editor to do that. This will take more time, as some copying is needed.
- I am paying for an expensive wireless kit, but the picture just comes and goes.
Wireless is a breakthrough in VA technology, but far from perfect. In the recent year spread-spectrum digital wirelesses began to pop up, and they are almost perfect, good enough for TV stations to use them on football matches, but they are cost really a lot of money today (over $40K last time I checked), and so not really usable for VA purposes. In the next few years, when the price of these comes down, we will see more of them on VA shoots. Cant wait.
Basically you should expect 70-90% performance from a correctly installed diversity UHF system, like a Modulus and a DX400. Installing a 4-antenna DX400 will take some time.
- How to make your VA picture better
There are not so many things what can be done to improve the VA picture. There is one common (and I mean common) mistake. The brightness of the video tap can be set on two points: optically (iris) and electronically (gain). You MUST open the iris first before setting the gain. If this is not so, you can add a lot of unnecessary noise to the image. Todays cameras are designed so that normally, for a correct picture the VA iris should be fully open, and gain set manually to minimum.
White balance also should be correctly set. Fortunately feature shooting happens in a quite controlled lighting. WB has to match lighting and film stock. Setting WB is easily done by eye.
From that point, there is not too much to do without physically changing parts. You should make sure that the best available camera is rented out if you want a good picture. Newer cameras have much better VA images. ARRI produces a separate CCD lens for S35 and Academy formats. Using the wrong one can cause some loss of resolution. Never mix PAL and NTSC video equipment. There are converters, but that only calls for problems. There are two kinds of IVS for 435s, the newer one can be identified from a small metal protector under the Sync in connector, and it has a somewhat better image. Moving the CCD closer (making the frame bigger on the screen) will give you a bit more resolution.
- Grounding hazards when working with crane or dolly
First of all, bad grounding is dangerous. In extreme cases, it can kill a human being. It does not happen normally, and a lot of things should go wrong for it, but you must always pay attention to it.
Bad grounding means current if flowing thru the chassis of some electronic device, like the metal box of a monitor, or the frame of a crane. It is not impossible, but rarely happens. It can also damage equipment, especially sensitive electronics.
The BNC connector is a pretty bad design by itself. While it makes for very low loss, and its quite sturdy, the ground and the chassis are not separated. Almost everything with a BNC connector on it has its electrical ground and chassis connected. That makes for nice ground loops. And everything connected with BNC cables will share the same ground. In practical terms that means that when a camera on a crane is connected with a video cable, the crane’s chassis gets connected to the video village. That is fine until there is only one mans input in the system. When the village is on Unit power, and the crane gets connected to the Electrical power for example, there could be problems. When the two are on the same genny, or when they are nicely grounded together – as they should be – thats OK. But different ground potentials can create a voltage difference between the two grounds, and then current begins to flow. Usually that shows by horizontal dark lines running on the screen. This can be eliminated to some degree by connecting a ground loop isolator (usually an opto isolator) on the BNC line between the crane and the video rig. The best solution is, however, to use the same outlet for both rigs.
Same thing happens when the camera is on a dolly, and they connect a charger. The charger is usually connected to the most convenient, closest outlet, and that can be dangerous for the reasons explained above. An easy solution is to disconnect the video line when charging the dolly.
Also, when an ext. sync line is connected from 24-frame playback, the same care must be taken.
- What is 24-frame playback and why I need it?
24-frame playback is needed when there are practical monitors in the set to be filmed. The main problem is that when you simply feed a picture in those, it will be 25 (PAL) or 30 (NTSC) frames per sec, instead of the 24 fps of the camera. A running bar will be visible on the screen. So we need to feed 24 frames (48 fields) into the monitors to make the bar disappear. Very few-badly designed-TVs can display 48 frames.
A 24-frame playback operator is someone with the equipment and experience, who can advise the props department on selecting the TV. He then checks if the playback is correct (you may need several units to find a working one) with a film camera, and sets up and operates the playback gear while shooting.
- VA for HD
HD is gaining more and more ground in the film industry, and it also changed VA applications a bit.
First of all, you can ask, why HD need a video assist? HD is tape, after all, and can be rewinded and watched back. That is a dangerous idea, almost as dangerous as using the processed negative from the camera to watch dailies. Rewinding the tape can damage it, it can be accidentally erased, and so on. On very small budgeted projects you may opt to not use a VA and play back the master tape, but that still be done only occasionally. On higher-end projects, a separate VA rig is necessary.
Today HD video assist recorders are just becoming available, and there will be a few years when they will be cheap enough to be used on every set. Till then, the HD signal should be fed from the DIT rig (or the camera itself) into HD directors monitors for live HD picture. The VA rig must be fed with SD (standard definition) image by a downconverter, or by a separate SD feed from the camera. From there its the same as film VA, except that a separate SD playback monitor must be placed on the director cart.
When you DO have a HD video assist rig, thats much easier - and better - for you. Care must be taken only that the DOP should know if he's looking at a HD picture going thru a recorder. Most DOPs and DITs prefer looking at an image as direct from the camera as possible. While the signal would be possibly going thru a HD reclocking distribution amp, its preferred that the DOP looks at a live image while rehearsing and shooting. Its unlikely, however, that the Director would also complain about looking at an image coming out of an HD recorder.
- What expendables a VA operator needs?
Here is a basic list I usually ask for as expendables.
DV tapes: Number of Days x Number of cameras used daily
DV cleaning tapes
Gaffer tape: 2” black, 1” white, some other colors
Monitor cleaner spray
Antistatic wet wipes
Dry baby wipes
Printer cartridge for video printer
Walkies with headsets
Crimpable BNC connectors, RG59 75 ohm (!!)