Flashing LCD's

[kencnnrs 8]

Hi all, tried googling this with no success, after watching numerous real world 737 videos (not only 737's do this) I've noticed, particularly on takeoff and landing that the LCDS tend to be flashing as if shorting out.  I was wondering if anyone knew the cause or reason for this.  Just curious is all.

[Kerlix 99]

If you mean in RW videos, its a "video illusion". I don't really know how else to describe it. Basically the camera is filming at enough FPS to capture the LCD's refreshing at 60Hz (or whatever their refresh rate is). 

 

The same thing happens if you look at videos with older computer monitors (think CRT) in the background. 

 

As for when it becomes more apparent, maybe vibration differences from the engines running at certain speeds is making is easier for the camera to pick up on it at those particular times.

 

I'm not a camera expert. At all. I'm sure someone can give a more detailed/accurate answer. 

[kencnnrs 8]

Just a video illusion was the last thing I would have thought it was.  Learn something everyday.   Thanks.

[scandinavian13 5,192]

Stroboscopic effect:

http://www.youtube.com/watch?v=rVSh-au_9aM

 

As Dave mentioned, it's the collisions between the refresh rates of the electronics and the capture rate of the video.

 

Also of note for newer simple cameras (GoPro, Contour, and smartphone cameras) is their use of CMOS processing (which is very vulnerable to vibration distortion):

 

Both effects could be causing the flashing that is not present in the real aircraft.  This is one of several reasons I always harp on YouTube "evidence."  Most people don't understand the shortcomings of recording equipment.

[joolsd 10]

That guitar video was amazing.

 

This is a interesting observation, About the panels. Eventhough they are flickering on the video, the human eye can't reconise it, or ay least the human brain can't. I have noticed that the airbus panels seem flicker alot more, maybe they run at a slower frequency? Or maybe they run faster? But they look slower?

[scandinavian13 5,192]

 

 

maybe they run at a slower frequency?

 

Based on the fact that America (Boeing) and a good number of European countries (Airbus) use different frequencies for power (60 versus 50Hz respectively), that could be a factor.  Then again, I believe the entirety of aviation runs on 400Hz as a standard, with no variation, so it might not be...

 

It could also be differences in the recording equipment:

NTSC (US) runs at 30fps and PAL (rest of world, essentially) runs at 25fps.  Could be that.  Who knows...

[hopskip 253]

Cameras will have different looking effects in different lighting conditions, with different aperture settings, and white balances. The same actual physical camera can go from a very steady looking picture of a screen to a very jumpy one in a few seconds by adjusting the aperture to get more or less light. The background light will change from dim to bright and CRT screens will go from smooth to flickering. Has something to do with the way CRT and some other screens scan. As in one pixel at a time from left to right, tracking top to bottom. When the Camera is sucking in as much light as it can, the 'left over ambient glow' as it were behind the electron scan is still picked up by the camera. But close the aperture to, for instance, look 'outside' the aircraft into daylight, the camera can't see the left over glow. Sometimes this will even be to the point that the screens look like they are turned off and black.

I recently went on a flight with a friend around Sydney, Australia in a Piper Archer.

To the eyes, the Radio frequency selector looked like solid orange numbers on the radio display, ie: 124.55

On the camera, it depended on how much ambient light and other movement the camera was undergoing. Sometimes it looked like it was flickering wildly.

[xxJohnxx 21]

I belive the Airbus CRTs refresh at 100Hz, but I haven't been able to find information about their LCDs.

[alex0987 8]

its because the light reflection, fps of the cam, the resolution, the focus. I may be wrong, but they definitely don't flash in real life.