A question about led lights.

[Bane]

Not been able to do m uch today cos I.ve hurt my back,so what better excuse to laze around and watch the BTCC coverage on ITV4?
Just been watching the Carrera cup and I've been noticing that the rear lights seem to flash,but not in any descernable pattern-looks totally random.Just wondering if this is some sort of safety feature of led rear light,or isi it something to do with the strobing effect of the lights in  the camera the same way houndstooth patterns used to screw up TV cameras.

NB sorry if I'm not making sense...on some rather strong painkillers! 

[stealthwolf]

Dunno if it's racing related or not but I've noticed modern cars do this when the driver brakes hard.

[Weston]

My understanding is that LEDs do flash at a very high frequency so when viewed through a camera they have that pulsing effect you've described 

[Nodz]

I've noticed this a bit on the tv, normally on Top Gear when they do slow motion shots, also remember Clarksons Ford GT doing it aswell

[JJ]

  

[rdfcpete]

^  

Even the reflection on the bonnet gives the strobe effect there. I thought as with flashing blue lights, flashing intermittent red lights were reserved for the emergency services and highway authorities?  

[sub39h]

there could be 2 reasons for this

the first is something to do with camera frame rate - the LEDs seem to play havoc with this and the LEDs appear like they're flashing. if you go on YouTube and look at spy shot videos of the RS3 you'll see countless examples of this

the second reason may be related to the fact they're brake lights. on modern cars the brake lights flash under hard braking (i.e. when ABS is triggered) as some studies showed it made people behind more aware of the brake lights and therefore they broke harder and avoided an accident. that said, i doubt race cars would have ABS. hmm...

[RedRobin]

Dunno if it's racing related or not but I've noticed modern cars do this when the driver brakes hard.

....I noticed this recently when a Mercedes braked hard in front of me on the M1. I had kept a decent braking distance anyway but it was a very good safety feature as traffic up ahead had come to a halt. It was good to have the extra alert. I assumed it was an OEM feature, especially as Mercedes pride themselves in such innovations.

[JJ]

Modern cars that have the flashing brake lights when hard under braking, both the brake lights and the high level brake light flash.  In the clip above, the high level light does not appear to flash.
As has been said, this is something to do with the framing rate of the camera and the electrical supply to the LEDs not being pure causing them to appear to be pulsing.

[Phil Miller]

when the mk6 astra came out 2yrs ago i pulled up behind one at lights and his brake lights were flashing alot of modern cars do this and its all to with safety

[sub39h]

Dunno if it's racing related or not but I've noticed modern cars do this when the driver brakes hard.

....I noticed this recently when a Mercedes braked hard in front of me on the M1. I had kept a decent braking distance anyway but it was a very good safety feature as traffic up ahead had come to a halt. It was good to have the extra alert. I assumed it was an OEM feature, especially as Mercedes pride themselves in such innovations.

yep i think the first production car that did it was the W221 Merc S-Class. at the very least that's the one that set the current trend for it

[tony_danza]

Anything on film is just the LEDs strobing, it's an oddity that they just leave be. You've gotta be very hard on the stoppers to make them flash to the eye.