Headlight Switch

[PaulSmith]

...

• my local MOT testing station and I would have to take some before and after pics at night to show you how the scatter can effect oncoming and well as traffic to the side.
  
• And there is the logic, the reflector wasnt designed to cater for bulbs that are 300% brighter. Most motorcycle reflector based headlights have scatter, which is good when using stock bulbs but bad with HID because the resultant scatter is so much brights it dazzles oncoming and adjacent traffic. Again i would have to take pics to hammer home the point/
  
• I'm referring to forward facing headlights not warning lights - http://www.legislation.gov.uk/uksi/1989/...ule/4/made
  
• You and I both know anything above 5k is the beginning of the blue end of the spectrum as far as human sight goes.
  
• Fair enough.
  
• Agreed.
  

Just to nip some things in the bud, I don't have a problem with HID's. My issues are, those telescopic kits  - the vast majority are cheap Chinese items that should be avoided like the plague because the baffles are so poorly designed that they add to the scatter problem. I have yet to see a kit that has correct amount of baffling (I made my own ages ago and the plan was to get a local enginering shop to make a laser cut version, but I never got around to it) And the colour, anything above 5k is asking to be pulled by the old bill and/or fail an MOT.

1 & 2) Can I assume that means you do not have any evidence at this time of there being a problem with the Fazers reflector?
3) Fair enough but this just highlights the difference between what you said and what you meant.
4) While true, it is worth noting that daylight on a cloudy day is about 6.5K, and 6K HIDs only look blueish if there is a 'whiter' light to compare against. My personal preference is for 5K bulbs as having the most 'daylight' like light, but I stress that is just my opinion. Most people I know who go for the blue lights (8K and higher) are not getting them because they think they are brighter (they aren't) but because they like the colour. When we were young, we would have been pulled for showing a blue light, but modern cops don't seem to be so fussed about it.

Re Scatter, I think you are rather missing the point. The MOT tests the DIPPED beam pattern to ensure it does not negativly affect oncoming road users. If you fail the pattern test, you fail the MOT. In this we are both agreed. However, the MOT does not test the intensity of the light, actually suggesting that the vehicle be moved closer to the target if the lights aren't bright enough. This means that if you have a scatter that directs light somewhere it shouldn't go, you will fail the pattern test, and since having a brigher (or dimmer) bulb doesn't change the pattern (or the scatter), it wont change the result of the test.

Finally, high beam is not tested because high beam is not used when there is oncoming traffic. This makes baffles and scatter irrelevant where high beam is concerned.  That leaves the only possible issue with telescopic bulbs the risk that they do not return to the correct centre point when switching from high beam back to dipped. This is controlled be a spring and there is a risk that this spring could fail. Since a HID bulb is expected to last ten times longer then a Halogen one, this is not a risk that should be ignored when using cheaper bulbs. However, it is still less likely then having the filiment fail in a halogen bulb.