All lamps are new and fitted with standard bulbs. The same test
voltage was used for each test. For an explanation of how to understand
the diagrams on these pages, which will open in a new tab or window for
you, please click here.
Halogen 5¾” 2C1 or
H5006 sealed beam (a particularly well-made Koito unit no longer
manufactured), on low beam setting: Reasonably intense and
well-placed
low beam hot spot, but narrow beam width, almost no
light on the road surface in near and midrange, and lots of upward light
that causes backglare in bad weather.
And the same H5006 (2C1) sealed-beam headlamp on high beam setting: Same
beam pattern, shifted slightly upward-leftward:
Cibie 5¾” round convex-face H4 lamp (most
efficient of its type) on low beam setting: Wider beam with better road
surface and RH shoulder illumination, but unacceptably low hot spot
intensity with excessive offset to the right:
And the same Cibie 5¾” round convex-face H4 lamp on high beam
setting: More intense straight ahead of the car:
Hella BiFocal 5¾” round flat-face H1
low beam: Extremely intense, large high intensity zone, well located close to straight ahead. Very
wide
beam width. Even lighting of the road surface. Enough light for
overhead road signs, but not so much as to cause backglare. No
stray light, careful control of glare light. Over double the luminous flux (light within the beam) of the sealed beam, and 55% more than the H4:
