Rated lumen output, I have discovered recently, is only a Lando (a fair Pilot!). So much depends on the state of your eyes, and the qualities of light and what is nearby or further away to reflect/collect light. With adjusted eyes and dialated pupils, even subluminal light can be the perfect brightness, and a couple lumens blinding. The state of your eyes is a moving target-- hard to know before dark exactly what you're going to need or want until well-experienced, so best to have options. I found tritium to be quite interesting, but also outrageously expensive and disappointingly fragile.