It’s of course less of an issue here in Scandinavia right now where the summer sun sets so late in the evening, but then at other times of the year we do plenty of driving in the dark. Especially during this spring, I suddenly noticed how I missed the green glow from the Rover instruments after I sold my early SD1. I found it much more pleasant than the classic white instrument lights from my Scimitar. But why?
For a long time, I used to believe that red light was best for your night vision. I think it was something about there being less contrast between the darkness and the red light which meant that the eye was less effected by the light. That however turns out to be nothing but an old myth, which possibly stems back to the days of processing film in darkrooms – where a red light was always utilised.
But this red light was a necessity for the reel of film – not for the human eye. White light would simply ruin the film, which was effected much less by red light.
However, research has proven that the human eye is largely unaffected as to whether the light is white or red – as long as it’s a reasonably dim light. And that’s the bit which really does matter, as a bright light will have an immediate and negative effect on your night vision, and it can take quite a while for your eye to recover and readjust to the darkness.
That’s because night vision doesn’t just come with an adjustment of your eyes normal physical mechanisms, but also requires a slow chemical process to take place within the eye. After about three quarters of an hour in uninterrupted darkness, your eye will have reached approximately 75% of its theoretical maximum night vision. But from there on, reaching those last reserves can take several hours. And even then, it only takes a single bright flash of light, and the whole process of readjusting to the darkness has to start over from scratch.
Personally I always drive with the instrument lights very dim. There have been vicious rumours circulating that this is simply down to the instrument lights on my old cars being inherently poor. If I’m to be entirely honest, there might just be some truth to those rumours. The instruments in my old Volvo Duett certainly weren’t capable of blinding you behind the wheel and those in the Scimitar aren’t much brighter. Both cars have that warm glow from the old-fashioned incandescent light bulbs – which I previously called white, but it’s actually more of a pale yellowish colour. And it’s actually quite pleasant in the dark.
But much as enjoy that warm glow from the dim light bulbs, it’s also the very same white light which has made me realise just how good the night time atmosphere was in my old Rover. Its instruments were lit up significantly better than in the Scimitar, making it much easier to read them with just a quick glance. Maintaining a constant 3000 rpm – which I knew would translate into a comfortable 110 km/h – was easy as could be. Furthermore, I felt that my night vision was less effected by the light too – despite the green light being a little brighter. The interior of the SD1 truly was an accommodating place to be during prolonged night travel.
I recently looked into the whole concept, and found – to my own surprise – that I haven’t completely lost my marbles. Green light does in fact have some advantages over other colours when it comes to affecting the human eyes night vision. It’s a complicated matter, as the eye is a highly complex thing, where each colour – be that green, red or blue – has their own advantages. But it seems that many agree that the best overall compromise might well be the green light.
All of which initiated several thoughts with me. But reflecting on the whole thing, I actually don’t believe that my sense of bliss experienced behind the Rover steering wheel was physiologically triggered or affected by the colours around me. I also doubt that Rover would have done significant research on the matter back then in the mid-seventies. Instead they would have most likely just chosen an instrument colour which best suited the rest of the SD1’s design. But it worked. Even now – some forty years later – under that futuristic David Bache shape, sat in those soft brown seats encompassed by all that brown plastic (which I of course couldn’t see in the dark, as the human eye loses its ability to differentiate between colours in the dark), the green, soft glow just seemed so harmonious.
Would it even be possible to improve the concept any further? Well, Rover clearly though so and came up with this answer for the early eighties: More green – and in the shape of digital instruments.
While that logic seems perfectly clear, the instruments were not. Though that has little to do with our eyes, and a lot more to do with the brains ability to quickly and unambiguously interpret various signals. After the initial craze for digital instruments has passed, we learnt that our brain interprets data – and not least changes – on an analogue instrument much faster than it does with digital instruments. So digital instruments – regardless of colour – turned out to be a dead end, and I was happy with my old SD1 being old enough to not have them.
Still I must confess that the aesthetics and the whole aura surrounding digital instruments does have a certain appeal. Yes, one of my many car dreams involves both digital instruments, retractable headlamps and a colourful velour interior. But right now, it’s the idyllic atmosphere of soft brown seats and green analogue instruments which I miss.
Have you given much consideration to the colour of the instrument lights in your classic? Do you too find immense pleasure from the calm night atmosphere created from the glow of old light bulbs? And which colour is your personal favourite for the instrument lighting? Come up with more questions yourself, and share the answers in the comments area below…