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Old 02-17-2013, 10:27 PM   #1
Toby Lang
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Default Question for Jeff Foster and Dave Kommel

How can a flash of visible light, e.g. a camera flash, trigger an infrared sensor? Or do cameras emit infrared radiation?

And who is the genius taking flash pictures before BOTH cars leave the starting line?
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Old 02-17-2013, 11:01 PM   #2
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Default Re: Question for Jeff Foster and Dave Kommel

Might it be the infrared focusing cameras use?
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Old 02-17-2013, 11:47 PM   #3
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Default Re: Question for Jeff Foster and Dave Kommel

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Originally Posted by Toby Lang View Post
How can a flash of visible light, e.g. a camera flash, trigger an infrared sensor? Or do cameras emit infrared radiation?

And who is the genius taking flash pictures before BOTH cars leave the starting line?
Sounds like the $50,000.00 electronics timimng system has a flaw ????
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Last edited by Don Kennedy; 02-17-2013 at 11:49 PM.
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Old 02-18-2013, 08:40 AM   #4
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Default Re: Question for Jeff Foster and Dave Kommel

The newer generation of cameras, containing high powered flashes and infrared, will trigger a photocell if it is aimed on the line-of-sight of the photocell.

Although they are designed to be operated in ambient light, the larger the photocell, the more prone it is to be affected by a bright flash or infrared devices.

This appears to be a rare case in which a photographer aimed his camera and it happen to be in the line-of-sight of the photocell.
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Old 02-18-2013, 09:37 AM   #5
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Default Re: Question for Jeff Foster and Dave Kommel

As you can see from another post I thought at least some timing systems used laser light rather than infrared. Is that true or just a misconception on my part?

Bill
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Old 02-18-2013, 10:31 AM   #6
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Default Re: Question for Jeff Foster and Dave Kommel

According to my conversations with Jeff Foster, it can happen. As to Toby's question about the genius shooting before both cars had left, if you have a handicap over a second, it's the only way to get both cars in the photo.

That said, with the newest generation of cameras with very good low light performance, we use flash much less frequently than in the past, but Pomona creates unique problems. You have the Musco truck on the west side of the race track putting out a tremendous amout of light on the starting and no light other than the ambient on the east side, therefore the only way to properly expose the east side of the car once it gets dark (or close to it) is to use flash.

The answer is to not shoot directly on the starting, but rather back behind the line, so that you have the stationary car in the foreground and the slower car as he is 20-40' out. The safe distance away from dead perpendicular is open to debate. Graham would probably like it to be 100 yards, while I think 10' is probably sufficient.
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Old 02-18-2013, 11:25 AM   #7
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Default Re: Question for Jeff Foster and Dave Kommel

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As you can see from another post I thought at least some timing systems used laser light rather than infrared. Is that true or just a misconception on my part?

Bill
No laser. I believe Compulink went from photocell to infrared on most of their timing systems. Still, infrared can also be affected if the camera flash is powerful enough and if is on the line-of-sight.
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Old 02-18-2013, 11:33 AM   #8
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Default Re: Question for Jeff Foster and Dave Kommel

toby what happened to ask that ?
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Old 02-18-2013, 11:52 AM   #9
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Default Re: Question for Jeff Foster and Dave Kommel

This could be cleared up if there was a demonstration of how it can happen? Surely intentionally aiming a camera to try and make it happen would result in it happening almost every time?
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Old 02-18-2013, 07:14 PM   #10
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Default Re: Question for Jeff Foster and Dave Kommel

First off, I just want to say that flash pictures should NEVER be taken until both cars have left the starting line. What do you think is more important, having a fair race without the possibility of a rerun or getting both cars in the photo? If we took a poll I don't think it would even be close. If you have to have both cars in the photo, go stand on a ladder at the 330' marker or at half track, whatever it takes, just don't take any flash pictures until both cars have left the starting line.

Have you ever tried concentrating on the tree with a camera flash going off in your face? I have. Back when I used to run my bracket car I was racing in Boise at the Nightfire Nationals. I was leaving off the top bulb. When the top bulb was about come on a flash went off in my face. When I could see again the second bulb was on. Not fun. I assume nobody would do that nowadays, but I wouldn't even want a flash going off behind me either. Somebody told me the photographer in the Dan Mason incident was about 10' behind the line.

I did a little research on cameras and they use infrared to trigger external flashes for better lighting. Dave, does your camera have the capability to use external flashes? If so, it uses infrared to control them.

I don't buy that it's the flash from the camera that's causing the red lights. If the sun reflecting off of a finely polished chrome plated front wheel doesn't trigger a red light, then how is the flash from a camera doing it? I bet it's the infrared from the camera that's causing it. Visible light is a different wavelength than infrared and it shouldn't matter how powerful the flash is.

And how many times does it happen when nobody notices it? Let's say a driver is about to cut a .150 light, but the photographer takes a picture at just the the right time and he gets a .025 light? Or a close red light?

I'm with Bill. I'd like to see a demonstration of this happening with just the flash part of a camera. If this can happen with just a flash from a camera, something is wrong. I believe it's caused by the infrared signal sent out by these cameras to control external flashes.

And once again, flash pictures should NEVER be taken until both cars have left the starting line. I hope you will tell other photographers this because there should NEVER be a rerun because of a photographer.
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