NICE!!!
Oh, there'll be no comparison with a Sten. If you put the Spark and Zebra on the highest settings at the same time, the output from your setup should be somewhere around three times the total lumens of a Sten (assuming a Sten output of 400 or so lumens). The Sten may reach a little farther if your buddies have narrow collimators in, but even a laughably weak 50 lumen light can throw incredibly far if you've concentrated the beam enough (and what's the point in that if you can't see a single thing in your periphery or in front of your feet?
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A word on watt ratings (for those who care to listen):
Don't trust them.Watt ratings are probably the worst way to compare lights. In the context of flashlights, watts can be thought of as energy consumption. When comparing lights, it's much more to do with the efficiency of a light rather than how much it consumes. One light that takes exactly 5.00 watts may be significantly brighter than another light that also takes exactly 5.00 watts, simply because it's more efficient at using that available energy. Someone may say that a certain light may be 25 watts (probably to impress their audience), but how well does it use that 25 watts?
A good example is the Zebra/Spark setup. Using a Relative Flux vs. Current chart from Cree and some approximate figures you can determine how many watts each lights draws on its highest setting. Doing the math you will find that the Zebra consumes just over 8 watts at 750 lumens, and the Spark nearly 5 watts at 500 lumens.
As I said before, throw has as much to do with the concentration of a beam as it does the output of a light. Your buddies' light may throw farther, but if it's an LED and it really does draw just 5 watts you may be surprised to find that your Zebralight alone puts out more total light than the diving light, because that diving light doubtfully uses a more efficient emitter or driver than your own.