Cygolite 150 vs Cygolite Hotshot 2W

2W on the left, 150 on the right.

Some years ago, the 2W was one of the best lower cost bright tail lights, a lot brighter than most lights at that time. Now, it's adequate, but LEDs are a lot more efficient, allowing brighter lights without overheating or using up a battery too fast.

First, the beam spread, shot indoors during the day, with a very dark exposure of 4 stops, -4 EV. Both lights aimed slightly downward the same amount, on a sheet of white paper.
The extra brightness of the 150 shows as yellow in photos instead of red.

Even the very narrow beam of the 2W on the left is effective out on the road, it widens with distance, of course. The narrow beam allows it to send more of it's light way down the road, but still wide enough at a moderate distance to cover all lanes.
The 150 is a lot wider, for coverage on curved roads and nearby drivers in another lane.

Both lights have spill light through the casing that works at close distances even from the side.



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Next, both lights aimed at a tan ceiling from about 6 feet away. This exposure is about 3 stops darker, -3 EV.
My photo software says the center beam is R:150 on the 2W, and significantly brighter at R:190 on the 150 light. (Using the RGB scale from 0 to 255). The difference is about .65 of an EV, where an EV = 1.0 is double the amount of light.

The 150 light's beam is wider than it is tall, so less light is wasted above or below eye level. So the light should be mounted vertically instead of on it's side.

I aim the 150 light slightly downward. That way, part of the main beam is still above eye level, and the bottom of this wide beam lights up the road behind me.

The older 2W is less effective if it's beam isn't aimed correctly, straight back. Both these lights are much less effective clipped to a seat bag, since it can't be aimed very well. Much better to mount them on the bike frame.