At just 56g, the Iota is Black Diamond’s most compact and lightweight headlamp.

A single switch controls all settings, making it easy to scroll through the various functions and light outputs. It is powered by a rechargeable lithium ion battery, charged via a supplied USB cable.

On full power, the Iota produces 150 lumens but can be dimmed to just four lumens. With a single charge, the battery is rated to last two hours on full power and 20 hours on the lowest setting, which produces just enough light to read a book.

The Iota is splash proof (rated to IPX4), which means you can use it in the rain, but don’t submerge it in a river.

Black Diamond markets the Iota as a lamp for ‘morning runs and post work scrambles’. After charging it up, I took my Iota on a dry caving adventure and used it exclusively for a week-long summer camping trip in Golden Bay. On the caving adventure, 150 lumens provided just enough light to navigate, but not enough to really see the cave. On the camping trip, it was great for reading at night and late night trips to the loo. What really appealed about this light, compared to the others in this review, was the weight. When worn it was barely noticeable and it is the most comfortable to wear of those reviewed.

For travel and lightweight summer tramping, the Iota is a good choice. If you’re heading on a backcountry tramping adventure or night trail run, you might want to consider a more powerful headlamp.