Hazardous Conditions
There are many myths about video cameras in general, and High Definition (HD) cameras in particular, regarding their vulnerability to the elements. Most of this is nonsense. If you think of the amount of electronics packed into a modern film camera, what makes an HD camera more susceptible to hazardous conditions? Very little.
There are a couple of cut-out switches in the camera to protect it from abuse. It will stop if the humidity surrounding the tape record drum becomes too high, and it has to be very high indeed for this to happen. A film camera would probably be equally in trouble. This safety trip is a wise precaution, for if the humidity surrounding the tape drum ever reaches a critical point the tape will, eventually, stick to the drum. You don’t want this to happen as it is not a field serviceable condition. The camera is going to need a whole new tape drum and that is going to be very expensive. I have been associated with a long-term shoot where a Panavised Sony camera was up a Scottish mountain in a gale for some considerable time; sensible precautions were taken, exactly as you would with a film camera, and there was never the slightest suggestion that the camera was threatening to shut down. There was a real chance that the crew would have to though!
There is a heat overload cut-out switch as well; this is mainly to protect the computer processors from overloading. I have never experienced or heard of this tripping out. I have been associated with an HD shoot in the Moroccan desert where the temperature was 110°F in the shade; the cameras worked perfectly. A personal experience of the reliability of HD cameras in this respect came when shooting in a studio during a particularly hot summer. As we neared lunch my camera operator put his hand on top of the Sony 750 we were shooting with in order to reach over for something and quickly pulled his hand away – it was very hot indeed. The ribbing on the top of the camera and under the handle is not a feature there to make the camera look more appealing; it is to better dissipate the waste heat from the analog-to-digital processor and do the job very well. When we broke for lunch my Gaffer, who had a voltmeter that could also be used as a temperature probe, measured the ribbing just before we switched the camera off for lunch – it was 32°C! I believe we really could have fried an egg on it. The moral of this tale is that the camera was still working perfectly, just as it had been designed to.
If you look under a Sony camera at the rear on the operator’s side you will see a small hole; this is the reset button. If the camera has tripped out then press a small, blunt object such as the end of a paper clip into this hole. The camera will not restart immediately. You need to take it where it is drier or cooler, depending on why it has tripped, and wait for the conditions to change. Removing the cassette and leaving the door open can help matters. The camera will come back to life when you press the reset some 20 minutes later. If you look carefully you will find a similar reset somewhere on most HD cameras.
Treat an HD camera with the respect you would give a high-quality 35 mm camera and you are unlikely to have any problems. Nevertheless, let us look at the precautions you might like to take.
24.2 Water
Please ignore the old adage “Water and electricity don’t mix.” The adage should be “Water and electricity mix only too well.” In fact, they attract each other. If there is the slightest sign of rain keep the rain cover handy. If you are going into a very humid environment take the camera and lenses in some hours before you need to use them and let them normalize. Keep a hair-drier handy in these circumstances to speed things up – but not set on heat please! Use it on cold or you may melt something significant. All just as you would do with a film camera.
24.3 Heat
Referring to the above, don’t put the rain cover on unnecessarily – it can cause a heat build-up as the fans cooling the computer processors won’t get their heat away as efficiently. If Sound have insisted, as they often do with the quietest of cameras, that you cover it with something to make it quieter, take that something off as soon as the take is finished. Remember the frontend processors are working full time just to give you a picture in the viewfinder and therefore they will be dumping waste energy, in the form of heat, even when the camera is on standby. This is one difference from a film camera.
If you are shooting on a very hot exterior location you would be very foolish not to put an umbrella up over a film camera to ensure that the film stock did not reach temperatures that would change its characteristics; please do just the same with an HD camera even if the reasons are different.
24.4 Cold
It is traditional to “winterize” a film camera if it is going to an extremely cold climate. HD cameras probably survive cold better than film cameras do. HD lenses will need just the same attention as film lenses. The biggest problem might be cables; they can become very brittle in the cold, especially BNC cables. Check out a few different makes of coaxial cable in a cold store to find the one that will survive.
Batteries in extreme cold are always a problem. Two remedies come immediately to mind: one is putting a DC supply cable into the camera and keeping the battery on the other end of it inside your clothing; alternatively, if you are shooting more formally, say on a tripod or a dolly, then before you leave home have some block batteries clad in 1- or 2-inch polystyrene and then have an outer case made for them in plywood. In really freezing conditions you could have a double-thickness polystyrene layer underneath the block battery and mount a suitable car headlamp bulb under it as a heater. Your battery will run down somewhat faster but while it has a charge it should be lively enough to keep the camera running.
24.5 Dust
All the usual precautions apply, such as protecting your lenses, setting up wind-breaks where possible, perhaps using the rain cover to protect the camera.
There is one both essential and simple protection an HD camera needs over a film camera. The most vulnerable parts of the HD camera, with regard to dust, are the tape transport mechanism and the record head drum. Very fortunately the gaps around the cassette loading door are not used in any way as cooling ports, so if you are in a dusty, gritty or dirty environment simply put some gaffer tape over the gaps between the camera body and the cassette loading door.
24.6 Gamma Rays
Now this is a bit sci-fi but bear with me, it could be important. One of the few things that can kill a pixel on the imaging chip is a gamma ray hitting it smack in the middle. At ground level there is very little chance of this happening; the Earth’s atmosphere absorbs or reduces the chances by a very large factor. On the other hand, if you are flying the camera at an altitude anything above 30,000 feet gamma rays are much more prevalent. I have only known one occasion where a camera has suffered gamma ray damage after flying and only one pixel was affected.
In all my time with both Digi Beta cameras and HD cameras I have only known one moment when several pixels were destroyed at the same time. Curiously, over a 24-hour period a camera in London was fine before lunch and after lunch had several dead pixels. The following day I had a telephone call from a crew in Prague in the Czech Republic saying there were a couple of dead pixels – very strange. Was there a sun spot that day or something? Who knows?
A pixel normally dies switched on so you will see a bright spot on the screen; it will be of the color relating to the chip it is on. Fortunately there are several ways to get rid of this bright spot. If you have missed it during shooting, and because it will always be in exactly the same place in the picture area, it is easy to eradicate in post-production. If you spot it before turning over then there is a better than 90 percent chance you can quickly solve the problem. Hold the black balance switch down for at least 3 seconds. The camera will now perform an extended black balance and an auto pixel check. This might take up to a minute and you may have to perform this operation eight or ten times to completely eradicate the problem. The camera has a sophisticated memory circuit in it and if it finds a dead pixel it will, for the rest of the life of the picture head block, take an average of the eight pixels surrounding the dead pixel and assign this average to the dead pixels’ output. The memory is sufficient to cover for up to 40 dead pixels. I have never known a camera reach anything like that number of dead pixels, but should it, the only solution then is to change the prism block and the three receptor chips.
If the auto pixel check fails to clear all the dead pixels – and you are only likely to be in this position if the pixel has only partially failed, which will give a dull colored glow on the screen – then the pixel memory correction can be initiated manually. I am not going to go into the whole procedure here, but if you need to do it in some distant part of the globe then ring your supplier and they will happily guide you through the process. If you are on your mobile phone make sure you have a fresh battery; it is not difficult but it is tedious. It’s very like playing an old computer game; you have to line up a vertical line and a horizontal line exactly over the pixel in question. With two million plus pixels per chip this can take a while and there is no scoring system, so it can be a thankless task.