N.B. – Opinions expressed are those of our correspondents and Motor Sport does not necessarily associate itself with them. – Ed.
Mr. Vyse states that apparently, an increasing number of popular cars equipped with rectangular headlights are causing dazzle to oncoming cars which does not happen with the conventional circular type. He then poses the question as to whether or not these rectangular headlights have advantages or are they merely styling gimmicks?
In answer to this question I would first draw upon my own experience. Until recently, I owned a Cortina 1600E which I changed for a Capri 1600 GT. The 1600E had circular headlights, supplemented by spots when on full beam. This equipment gave what I considered to be a good light pattern at all times, in all conditions, either on full or dipped beam. The Capri has rectangular headlights and these, in my opinion, are “not in the same street”. The light pattern on both full and dipped beam is an extraordinary shape and indeed, in some conditions, extremely distracting. In fog or mist, from the driver’s seat, strange narrow beams can be seen leading off in all directions above the front of the bonnet. However, in reply to Mr. Vyse’s statement about dazzle I must say that I have not experienced irate oncoming drivers indicating that my dipped headlights are dazzling them.
Secondly, I draw attention to a popular car range, the Ford Escort. At the bottom circular headlamps, presumably because the end of the range the 1100 is fitted with are cheaper. Moving up the range to the 1300 Super and 1300 GT models, these are fitted with rectangular headlamps, perhaps because a designer somewhere along the line thought they would “look nice”. However, moving up to the top end of the Escort range, the Mexico and the RS1600 are fitted with circular headlamps, albeit that they are of the halogen variety.
It is my submission that Ford consider these circular headlamps to be more efficient and to create a better light pattern more suitable for the anticipated performance of these “top-end” models. You will be aware that the latest Capri 3000 now has twin circular headlamps to replace the original rectangular variety.
It would certainly appear that, in fact, rectangular headlamps are less optically efficient than their circular counterparts. Verily Mr. Vyse, they are the result of a stylist’s whim.
Perhaps both Ford and Lucas would like to throw some more “light” on this interesting subject!
D.J. Farrow – Great Bookham.
[The BMW 2500 has dual circular headlamps. – Ed.]
Your correspondent, Mr. B. Vyse, is partly correct in his assumption that rectangular headlamps are a gimmick. The story, so far, is as follows. The continental headlamp manufacturers standardised on a single design of headlamp bulb. This No. 410 bulb has a 45 watt main beam filament and a 40 watt dipped beam filament. They also agreed on certain beam characteristics for the dipped beam. Headlamp makers in the rest of the world developed more powerful, and more long-lived, all-glass headlamp units.
With the standard No. 410 bulb it is difficult to get enough light from the low-powered 40 watts filament at the all important top edge of the dipped beam. In order to collect as much as possible of the available light the reflector was extended sideways. This lateral extension produces a real improvement in the amount of light near the top of the dipped beam of continental headlamps.
Directly rectangular headlamps appeared on continental cars British stylists demanded that they too should have similar shapes for British cars. What was particularly stupid was that in the mid-Sixties the fashionable, but inferior headlamps were only fitted to the faster and more expensive models in a range. The poorer buyer, who purchased the cheaper car, was supplied with the more powerful round headlamps, although he had a car which was not so fast—at least not so fast by day.
The position was partly restored when Lucas produced a small rectangular all-glass headlamp unit which is now a well-developed and powerful lamp with 75 watts for main beam and 60 watts for dipped beam. But in the latest Capri this unit has been supplanted by a metal and glass unit with the No. 410 bulb. Thus seeing has been sacrificed on the altar of standardisation. For now the same front-end design can be used on all European Ford Capris.
Having a variety of headlamp shapes means that the cost and availability of spare parts is increased. Using metal and glass headlamps means that they will deteriorate in their performance. And using the No. 410 bulb means that there will be less light available than on previous cars with round units.
I said this was the story so far. I fear that there will be worse to follow as stylists wrest more of the control of vehicle design away from engineers.
J.B. Davey – East Finchley