Washed-out infra red camera

[Cashwalker]

I've got a cheapie security camera that is getting completely washed out by the stage lights.

It starts out in color until the lights go up. Then it was black and white... I figured it was just because of the intensity of the lights.

My first instinct was to move the camera farther from the stage, which we wanted to do anyway to get better coverage of the full width of the stage.. But that seemed to make it worse.

I then tried holding a congo blue gel in front of the camera, with no change in the picture. From that, I realized that it's the IR light from the stage lights that was reflecting off the walls, registering in the camera, causing the problem.

Any solutions that anyone could think of?

I'm thinking a piece of glass might work like they did on Mythbusters trying to fool IR sensors.

 

[cprted]

I may be missing something here, but I've always used IR cameras to see the stage when it was blacked out, otherwise the normal program video camera does the trick if I can't cleary see the deck from where I'm calling.

A piece of glass won't do anything for your issue. IR cameras can't see through glass.

 

[thatactorguy]

I'm a bit confused as well, but your situation reminds me of an issue I ran into some years back; perhaps my solution will help you...

We use a 2.4Ghz X10 Wireless camera for our monitor so the actors in the greenroom can see their cue coming. Remember those popup ads on the internet some years back? One and the same. $79.95 later, I had the two camera set with a controller to switch between cameras, and some table lamp controller as a "bonus"...

I was running into a similar problem with washout, but never went to b&w. I tried adjusting the color, brightness, contrast, all that on the television itself, but the camera seemed to adjust itself to compensate. I use a lot of R33 (No Color Pink) on our shows and found a slice of something resembling R56 or R59. On a whim (or stroke of genius), I placed that 3"x4" piece of gel in front of the lens, and that solved the problem. You may have been on the right track in putting gel in front of the camera, but it may just be the wrong color. Try the dark pink/violet family. The view on your monitor will darken, but you shouldn't have as much washout...

 

[Cashwalker]

Maybe I should rephrase the setup a bit.

The camera is normally a color camera. It has 6 visibly red IR LED's surounding the lens. With the house lights on, it looks good enough. Turn the lights out, and it's marginally good at distance with IR, but seeing in the dark isn't critical. Once the stage lights are on, the walls (painted beige this show) must be reflecting a lot of the IR from the stage lights, and the B/W picture becomes mostly white. We can't make out specific faces.

We worked on the problem a bit tonight. Yeah, the glass didn't work. I could see a difference actually, but it didn't block much, and it reflected the LEDs back to the camera, so I taped those over anyway.

I didn't see the pink suggestion until now, but I'll try it on Saturday.

We moved it a fair bit closer,and we can at least make out a face, but it only covers 2/3 of the stage.

We've got a few old Sony security cameras in storage. never bothered to try them out. They output standard video that a TV could handle, right?

 

[skapp]

security cameras normally use a coaxil cable with BNC connectors and most of the time require either 24v or 48v (make sure you verify what your camera needs!) power on a seperate line.

 

[ruinexplorer]

The issue that you are having is because the camera is most likely auto sensing the light levels. When you have the house lights up, the ambient light is pretty even across the board. When you are under stage lighting conditions, only the part of the set that you want to be seen is lit, but the camera is sensing the entire area of its vision. The auto sensing mechanisms are trying to balance out the image over all. Your cheaper, home security cameras will not allow you to have much, if any, menu control. If you are using a business type security camera, then you may be able to turn off the auto sensing (especially if you are not looking to use it during black-out situations). If that is the case, you will want to set your iris and gain for the brightest look in your show. If you have a particularly dark scene, you may run into some issues of not being able to distinguish faces again, but IR illuminators may help you out for those situations. If you can't get IR illuminators in that situation, you may want to consider two cameras (one for bright scenes and one for dark scenes) and have a simple switcher for your monitor.

 

[Cashwalker]

I don't think it's visible light level, because a congo blue gel didn't change the picture at all, other than reflecting the IR led's back to the camera.

I looked at the cameras we have, and they're 24 VAC with BNC outputs. We'll try them out before our next show. Then it's just a matter of where it can be mounted, and how I'll be able to make use of the signal.

 

[ruinexplorer]

I don't think it's visible light level, because a congo blue gel didn't change the picture at all, other than reflecting the IR led's back to the camera.

I looked at the cameras we have, and they're 24 VAC with BNC outputs. We'll try them out before our next show. Then it's just a matter of where it can be mounted, and how I'll be able to make use of the signal.

I wasn't talking about the visible spectrum. The adjustment is most likely based off of the infrared spectrum. With Congo Blue, you are blocking out very little of the IR spectrum (based on the assumption of the curve of the upper end of visible red). This is why your camera is setting the balance that is creating a washed out look where you have the most visible light (also a concentration of IR light). Brilliant Blue actually blocks more of the IR than Congo Blue while appearing lighter in color (so theoretically would work better for this application). Remember, IR is heat energy. The more IR that a gel absorbs, the faster it will burn. So, even a gel that is blocking almost the entire visible spectrum will often allow the IR to pass to allow it to last longer.

The other option is to get some IR illuminators and add them to your stage. If they are strong enough to add "fill" light to the rest of your set, your camera may adjust accordingly.