HDSLR camera sensor and lasers

[sbk]

I'm wondering how such a SLR sensor from an HD camera would be prone to laser induced damage, even with a properly settled beam attenuation map, so the laser power will not exceed 10-15% of the max power where the camera will be located? The show will run on full darkness so no need of mega power to obtain a nice effect. And the camera will be placed at 15-20 meters from the laser apertures.

As we can see horrible video footages on youtube et cie, most of the time showing a line across the picture appearing right after the laser hit the camera...

I have a bit less than 4 watts in my center RGB (1.8W 640, 1W 532 and 1W 445), and two satellites with 1W 532 + 1.8W 445, the three with a divergence of 1.5 - 2 mrad... I have a show tonight and a friend planned to film it, but I'm quite reticent to damage its 10'000$ camera... And don't had the time to set up a dead zone (moreover, a completely dead zone will make the show look not that nice...).

[flecom]

almost all those videos were Canon 5D Mark II's...

my Canon 1D and Canon 1D Mark II have taken a lot of hits and they are both fine (1.3x crop CCD and CMOS respectively)

anyway cameras are the cheap part, the lenses are whats expensive

[masterpj]

Heres a trick i do.
Place the camera with the lens covered so no laser can get in, them draw a cross with the laser projector on so the cross is in the middle of the covered lens part.
then draw a 0% beam attenuation map over it *wider then needed* then begin to draw a 100% power square slowly so you can pricisly not let any beams get in and still give the impression your not lowering power on a certain spot

I use pangolin LD2000 not sure if you can do similar in you laser software.

[flecom]

Heres a trick i do.
Place the camera with the lens covered so no laser can get in, them draw a cross with the laser projector on so the cross is in the middle of the covered lens part.
then draw a 0% beam attenuation map over it *wider then needed* then begin to draw a 100% power square slowly so you can pricisly not let any beams get in and still give the impression your not lowering power on a certain spot

I use pangolin LD2000 not sure if you can do similar in you laser software.

thats fine when you have one projector, but at large LEM's its almost impossible to "cut out" a camera from all the projection zones

but ya, ideal scenario you would not be hitting the camera because you are not going to get good images anyway... although I did get some pretty weird pictures when I got direct hits

[mccarrot]

I would NOT put a DSLR at 15 meters with a 4W projector, you need to have more distance to let the beam divergent more.

A lens of a camera is designed to collect as much light as possible, and the sensor does not have a adverse response like humans (looking away, etc)

I think if you calculte the NOHD this would (probbably) be a safe distance for your camera.

Giving the facts:
4 mm beam @ aperture
3500mW @ aperture
2 mRad divergence
MPE 10mW/cm^2 (proposed by ILDA for scanning beams)

You end up with a proxamte safe distance of 100meters between laser and camera.

But these calculations are based on a 7mm pupil aperture, a aperture of a camera (especially DSLRs) are much bigger.

[mccarrot]

Oh, and I would also not put a photographer at 15 meter distance from a 4W projector.

adding ND filters in front of the camera and boost the ISO of the camera could be a solution. Most DSLR's film with the aperture wide open.

[flecom]

again, I have been 3 meters from a 6W projector without issue with my 1D and 1D mark II

it seems all the cameras that are exploding when hit by lasers are the 5D Mark II's

an ND filter is probably a good idea if your worried

[mccarrot]

And you where scanning your camera with 6W @ 3 meters, than You are a lucky person or you havend find the bad spots yet.Also note there is a big difference in pencil beam or fans with anchor point, and circles. The pulse time of a circle can easily be 1000x faster compared to the pencil beams, ans causing less harm. If this particular laserhow had used pencil beams and lowered the scanrate there would be a very high chance your camera would be damaged.Next time if you film a 6w projector @ 3 meter and your camera does not get damaged make sure you buy a lot from a lottery.There are also many forum members here who damaged a camera with less power and longer distance.

[White-Light]

I think its down to luck as much as anything and the camera sensor.

At the recent UK LEM, one show got away from Rob and was accidentally audience scanned whilst my HD video camera was on. The centre laser was 3 watts RGB. The outer satellites still multi-watt. I can detect no problems from exposure from around 20 foot from the aperture.

Similarly, my small Casio camera has been regularly exposed to around 1.5 Watts 532nm in a nightclub from around a similar distance 20-30 feet with no sensor damage. (I know the laser to be a Laserwave 1 watt unit that's quite "hot"). Same with my eyes obviously as I was filming (I have had retinal photography so know they're ok) - I wasn't responsible for the lasers before anyone accuses me of recklessness / law breaking!

Yet by the same token, you hear of cameras being damaged at much greater distances by much lower powered lasers.

At the end of the day, with any camera you take a risk unless you BAM it and set the zone to 0% which then creates a hole in the pattern that spoils any recording. If you BAM it above 0% then obviously the risk is there but reduced.

Personally I'd BAM the camera as tightly as possible around the aperture and set a BAM at maybe 10% - that's still 400mw. There's a risk but its much lower than at 4 watts!! Remote control or an operator with their back to the laser at all times is the only control option (although watch for reflections off lenses and tripods if sat in front). If you find the BAM too obvious then obviously you need to up the power by reducing the BAM attenuation but with every step up the risk increases.

Beyond that the only safe option is not to film.

[DanBarlow]

Real film gets a new sensor each frame... check your area for hobbyists. 16mm is HD quality and even Super8 looks pretty good digitized.