Protection For Cameras From RF
Published : 22nd December 2004
>We're heading to France in a few days for a doc shoot and we've received permission to shoot in the Eiffel Tower. However, we have been warned that because of the amount of transmitters on the tower that cameras can be seriously damaged and they recommend some kind of shielding.
>I heard there was a company in Ohio that makes a fabric that can reduce the problem, but can't seem to find anything about them -- any ideas or leads? Or, for that matter, any other flashes of brilliance? And, yes, we're bringing black-wrap and aluminium foil...
Chris Cardno writes:
>because of the amount of transmitters on the tower that cameras can >be seriously damaged and they recommend some kind of shielding.
>But anyway, what are you shooting? Film? Video? Can you be more specific?
>My first suggestion might be to get hold of a simple, consumer-type camera for your shots from the tower. It's likely to have less-sophisticated electronics than a pro unit, and if it goes belly-up you won't be left stranded and in hock.
Dan "nicht schuldig!!" Drasin
Marin County, CA
Over the years I've shot more times on and around the Eiffel Tower than I wish to remember. (Where else do the Brits and the Americans want to shoot when they come to Paris.) I've used everything from Beta SP to DV to DigiBeta. There are a lot of transmitters at the very top. I have never dressed the camera to protect it from RF nor have I ever had a problem Maybe I'm just dumb and lucky.
>I do carry a roll of thin lead foil (about 2-3x thicker than black wrap) with me. It is sold in hardware stores here as something to shore up old apartment walls crumbling with humidity.
>The biggest problem shooting at the Eiffel tower is wind. The biggest problem shooting the Eiffel tower at night is the cost of the broadcast rights for the lighting. It's copyrighted.
The best and easiest way to reduce the chances of RF interference would be to physically keep away from any aerials that you can see. But in the case of the Eiffel tower or shooting on ships where there is radar, would be to take along a short length of stranded single core cable with a crocodile clip on each end.
>Clip one end onto the camera body with exposed metal work, the carry strap post is best, and clip the other end onto the structure of the tower or decking where you can get good electrical contact.
>This 'grounds out' the chassis of the camera and diverts away electromagnetic fields and should reduce the chance of RF getting into any circuitry.
>Covering the camera in tin foil etc. still leaves the camera at 'floating' potential and is no more effective than the metal casing of the camera. RF could also be picked up on the lead from a sound recordists mixer umbilical, so grounding the chassis parts of the camera which is connected to cable screens, should eliminate this.
>I do carry a roll of thin lead foil (about 2-3x thicker than black wrap) with >me.
>I mentioned this on one of the lists a while back, but I'm now shooting a series at a Veterinary Medicine college, and we're in and out of lead vests all the time when shooting in Radiology and some surgeries. I've discovered that the lead vests don't interfere at all with wireless microphone transmitters. This leads me to suspect that covering the camera with thin lead foil isn't going to do much to protect it from RF.
>George Hupka writes :
>This leads me to suspect that covering the camera with thin lead foil >isn't going to do much to protect it from RF.
>So I can get rid of the lead? Need to lighten the load...
For complete protection of sensitive electronics from RF, you need an effective "Faraday Cage" :
Eastman Kodak Company
class="style7">>For complete protection of sensitive electronics from RF, you need an >effective "Faraday Cage":
>So if I'm reading those sites correctly, it would be very hard to shield the entire camera since the gap you'd have to leave for the lens would be larger than the wavelength of the RF frequency you need to block.
>But I wonder if a "Porta-brace-style" cover that protected the majority of the camera wouldn't at least decrease RF interference in high RF environments? Or is the camera body already doing that to some degree?
>It may also be possible to build a better cage around the camera's internal electronics - I'm guessing it would have to be designed into the camera, though...
>This does give me a great idea for a clause to add to rental contracts, though :
>"We assume no responsibility for camera problems due to RF interference unless client supplies a proper Faraday Cage for the equipment."
Steven Gruen writes:
class="style7">>So I can get rid of the lead? Need to lighten the load...
>Lead will be no better than aluminium foil. There's no reason to use lead for anything but ionising radiation (X-rays, nuclear radiation, etc.)
>And neither will do you much good if you haven't created an effective,
grounded "Faraday cage."
Marin County, CA
Dan Drasin writes :
class="style7">>Lead will be no better than aluminium foil. There's no reason to use >lead for anything but ionising radiation (X-rays, nuclear radiation, etc.)
>Actually, the lead has been in the bag since the days when I used to work on a medical magazine for tv. We taped around x-ray machines quite a lot.
© 2018 copyright CML - Cinematography Mailing List all rights reserved