All lamps are new and fitted with standard bulbs.The same power supply and light tunnel were used for each test.
Standard DOT halogen sealed beam, low beam setting: Reasonably intense and well-placed low beam hot spot, but narrow beam width, poor foreground lighting and lots of upward light that causes backglare in bad weather. (2C1 unit photometered; 2A1 units extremely similar).
Standard DOT halogen sealed beam, high beam setting: Same light distribution as on low beam setting, only shifted slightly upward-leftward. (2C1 unit photometered; 2A1 units extremely similar)
Stanley ECE H4 unit, low beam setting: Reasonably robust and wide beam pattern for what it is. Hot spot is rather far over to the right. Fair control of upward stray light that causes backglare in bad weather.
Stanley ECE H4 unit, high beam setting:Not much to complain about here. Reasonable intensity and spread.
Hella ECE/DOT (SAE) harmonized H4 lamp, low beam setting: Good hot spot intensity and placement, but distractingly streaky foreground light and poor control of upward stray light. This lamp would be dramatically reduced with a thoughtfully-designed bulb shield, but unfortunately it hasn't got one.
Hella ECE/DOT (SAE) harmonized H4 headlamp, high beam setting: Narrower and less intense than the Stanley, but still decent.
Bosch polyellipsoidal (projector) ECE H1 low beam unit: The clear winner in this comparison.. Ultra-wide beam with no stray light, carefully controlled uplight for overhead signs, and a very intense and well-placed hot spot.