OK So I finally managed to get some shots on the lake in spite of -17C temperatures. Some control or reference photos were also shot just to give some relative comparisons.
I have a couple Blackburn Voyager 2.0 Front Light's mounted, which some people have stated are junk, but I personally find just fine in the city and for day-time running. And just to show how far things have progressed, I also hooked up one of those Petzl MegaBelt 10W halogen headlights from 20 years back too.
In case anyone is interested, those photos were all handheld at ISO 100, f4 and 1sec which were the settings the guys at the MTBR forums decided were appropriate for high power beam shots. Normally they use a 4 sec exposure for commuter lights but I used a uniform time just to give a realistic relative reference. And the coverage is fairly representative of whats in front of you. Real life does have less contrast extremes.
The distance to the wall is 35 feet. The sets of lights were mounted on the same bicycle, except for the headlamp of course.
This is the Petzl which puts out about 35 lumens, is zoomable, and is pretty dismal at either setting.
This is the Blackburn Voyager 2.0 Front Light (two of them). A very narrow beam that lights up stop signs two blocks away but doesn't give great lighting immediately in front of the bike. The Blackburn specs claim 30 lumens and I'm thinking thats a typo cause this is way more than that. A Knog Skink Strobe claims 100 lumens and the Blackburn blows that away so I'm thinking probably 300 lumens.
The pairs of high powered LED lights weren't aimed directly at the wall - they were aimed slightly downwards so that the area in front of the bicycle would be illuminated and the light would not be in the eyes of oncoming traffic.
The high powered LEDs are all made by the same company, use exactly the same P7 Seoul LED, are rated for the same 0.75A power draw, the same 900 lumen output, and were connected to the same power supply and aimed squarely. The difference is entirely the design of the lens assembly.
This one uses a standard 35 degree cone shaped beam identical to what's found in most flashlights and bicycle lights.
The light beam is narrow, and driving on rough roads would still be difficult because it would be hard to access the best route to pick. It has good 'reach, but poor 'spread'. I really don't need to see stop signs four blocks away, but would like to see whats coming up. Also, if aimed upwards to disperse a little more light, the beam will hit oncoming traffic - same as a high beam.
And this other one uses a compound 15/45 degree spread to distribute the light horizontally where its most useful while restricting it vertically to keep it out of the eyes of oncoming traffic.
Not only is a broader area illuminated more completely with the 15/45, it would be very feasible to drive safely with LESS light. Therefore a single light could be used instead of a pair to give better run-times and still provide excellent lighting. And this one is actually easy on the eyes while still being very visible!
Manufacturers can manipulate apparent headlight brightness by using smaller cones. It lets them project the same output into a smaller area producing a brighter light or longer run-times or both. Both 10 and 15 degree cones are even more common (and more useless) than 25 or 30 degree cones. Many beam shots are taken in a manner that demonstrates how far the beam will reach - not how well/poorly the beam illuminates the first 30 to 40 feet in front of the cyclist - which is really the most practical thing for a cyclist.
Personally I HATE tunnel-vision and conical light distribution might be better than nothing, but its not the best aid to safe driving. I need, not only to see where I'm going, but where I might have to go to avoid an obstacle, and also want to see a skunk or raccoon BEFORE it crosses my path!
'Pencil' beams make sense for automotive driving lights where they supplement the reach of high beams at high speeds. Effective near-reach lighting is more appropriate for cyclists based at their driving speeds and the need to avoid what some cars can simply drive over.
So IMO most bicycle lights don't do the job half as well as they could if the engineering emphasis was put on useful light distribution. Which is pretty much why I decided to scrape together something more practical for my own use.
OK So here are some shots out on the lake where there are no range restrictions and no supplemental light sources.
The Petzl just disappears even in a one second exposure. You can just barely see it if you look really, really, really closely.
The pair of Blackburns makes out better but I wouldn't want to drive off-road with it.
A pair of spots is a lot better, but still doesn't quite do it for me.
A combination of reach and spread provided by 3,000 lumens of light directed by paired lenses gives a coverage I can drive at any speed with.
One thing to keep in mind is that these are winter conditions when reflectivity is at a maximum. Spring, summer and fall conditions need a lot more light, on-road and off-road. Asphalt and wet ground both really suck up lumens.
This isn't a $9.99 solution and may not be to everyone's liking, but compared to some of the $900 solutions out there - it looks great to me!