Question for Jeff Foster and Dave Kommel

[Toby Lang]

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?

[Winklovic]

Might it be the infrared focusing cameras use?

[Don Kennedy]

Originally Posted by Toby Lang

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 ????

[SSDiv6]

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.

[340Cuda]

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

[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.

[SSDiv6]

Originally Posted by 340Cuda

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.

[larry dowty]

toby what happened to ask that ?

[Toby Lang]

I just found out there is a video of this and being the video guy that I am I checked it out and here's what I found:

Here's the frame right before the red light comes on:




Here's the next frame when the red light starts to come on:




Here's the next frame when the red light comes on fully:




And here's the next frame after the one above:




It's hard to tell by just looking at the photos, but in the last frame you can see the reflection of the flash off of the left front corner of the car.

You need to download each picture and scroll through them and it's easy to see. I just use Windows Picture and Fax Viewer and use the right arrow to go to the next picture.

If I were a betting man, which I am, I would bet the camera that took the picture has the capability to trigger external flashes. And to trigger the external flashes the camera uses infrared.

I don't know how external flashes work, but it makes sense that you would have to send out a signal from the camera to the external flashes before the actual flash happens so the flashes are in sync.

The video has a frame rate of 30 frames per second. Which means each frame is .033 seconds apart.

So I believe my hypothesis was correct in my post yesterday.

[FrankChastain]

Look at the O'Reilly sign at the right hand top corner on the sign. Then looking at the passenger side of the car about where the parking light is. According to this the car hasn't moved in any of the four pictures...Just an observation....

Originally Posted by Toby Lang

I just found out there is a video of this and being the video guy that I am I checked it out and here's what I found:

Here's the frame right before the red light comes on:




Here's the next frame when the red light starts to come on:




Here's the next frame when the red light comes on fully:




And here's the next frame after the one above:




It's hard to tell by just looking at the photos, but in the last frame you can see the reflection of the flash off of the left front corner of the car.

You need to download each picture and scroll through them and it's easy to see. I just use Windows Picture and Fax Viewer and use the right arrow to go to the next picture.

If I were a betting man, which I am, I would bet the camera that took the picture has the capability to trigger external flashes. And to trigger the external flashes the camera uses infrared.

I don't know how external flashes work, but it makes sense that you would have to send out a signal from the camera to the external flashes before the actual flash happens so the flashes are in sync.

The video has a frame rate of 30 frames per second. Which means each frame is .033 seconds apart.

So I believe my hypothesis was correct in my post yesterday.