Front view of the Black Diamond Cosmo packaging


In the outdoor store, right next to PETZL’s TIKKA we found the BLACK DIAMOND® COSMO. Pretty much a competing product to the TIKKA, very similar in price, size and brightness. Which made us pretty curious, because the COSMO is quite popular too. So, we bought one and put it to the test.

Just like the TIKKA, the COSMO is a small affordable headlamp for everyday use. It uses 3 AAA batteries, weight is 94 grams (3.3oz) and it’s rated IP X4 water resistant (splashing water). It comes in 7 colors, including black, white and grey – the actual colors are orange, yellow magenta and blue.

Front view of the Black Diamond Cosmo


Regular price is EUR 29.95 / US$ 29.95. Online, you may find it for less.


What can we tell? Unpacking it, we expected better from Black Diamond. The style of the COSMO is kind of edgy and junky – reminding us a bit of a 2009 Cadillac Escalade. Holding it in our hands we instantly get the feeling it must be heavier than a couple of other headlamps we’ve tested before. And indeed, the scale shows an extra 10 grams, compared to the TIKKA for example.

Over all, we don’t get too excited yet. But let’s give it a chance in our closer look.

The headband: Again, we need to ask ourselves what went wrong in the history of headbands. Our readers know, we’re no friends of printed headbands – like we keep seeing them lately. We still prefer the woven ones. To us, they look better, have a smoother feel and actually take up sweat. Much better than the printed ones.

Stretched head band of a headlamp

The COSMO comes with one of those printed head bands. They look nice at first, but instantly become quite dull, as soon as they are stretched. The print breaks open and the white elastics underneath can clearly bee seen. Sorry, it just doesn’t look good!

The outer plastic parts are ok. They make a pretty sturdy impression to us. So, no worries about dropping the COSMO and breaking it.

Bottom view of the Black Diamond Cosmo
Cheap character of the Cosmo plastic parts

The battery compartment unveils the character underneath. The parts inside are not well designed at all. We’re looking at completely not-designed plastic parts, non-matching textures and different sorts of screws.

Now, some of you may say this is not important at all. We agree with you. But for us, it’s one of the typical indicators, telling us how much effort and appreciation went into the making the whole(!) product.

Please take a look at the paper stickers and the love-less design of the interior plastic parts. That’s not state of the art product design. We recommend BLACK DIAMOND to keep an eye on that or give us a call. We know how to do it right.


The over all handling of the COSMO is good. The longer we play with it, the less careful we get. That’s a good thing, because it proofs the COSMO is a real outdoor product. We don’t get the feeling we needed to handle it over-carefully or put it in a protective pouch before we stash it into a backpack.

Opening the battery compartment of the Cosmo

Now, opening the battery compartment is a different story. It confirms our impression from the very beginning. The COSMO is not really designed with the customer in mind. Everything may work ok, but buying a product from a major outdoor company we expect a product designed with a lot more emotion and heart. Instead, we’re looking at emotionless chinese engineering. Sorry for that!

Inserting batteries in the Cosmo

To the point: In full daylight we can hardly see how to insert the batteries. The markings are so weak and dull, we only can see them in certain angles of light. The battery contacts do not only look cheap, they also don’t hold the batteries in place very well. Every time we opened the battery compartment so far, one or two battery fell out – on the ground. That’s nothing you want to have outdoors, in the dark, maybe in snow!

3 AAA batteries in the Cosmo

The two main housings are held together with a plastic ribbon, instead of a hinge. So you can’t lose half of your headlamp. To be honest, the ribbon must be a cheap fix only. If the product was thought out well from the beginning, there would have been a thousand better solutions…

Battery compartment not fully closed

Closing the battery compartment works fine, with a nice and settle snap. Sometimes, it’s a bit of a fumble to get the two parts in place before they actually close. However, we don’t want to be too negative. And luckily you don’t need to change batteries all the time.

The Cosmo adjusted downwards

Very positive thing is the adjustability. The COSMO has an adjustment angle of approximately 50 degree – done in 3 steps, each 17 degree. Which is standard and more than plenty. What’s very nice about the adjustment, is the settle click between the three angles.


The on-off switch is always one of the more critical parts of a headlamp. Wearing a headlamps on the forehead, we need to find and actuate the switch without looking at the product. Pushing the switch must work in all situations, even with thick gloves in winter.

And, the switch needs to give proper feedback to the fingers. Very important, because most headlamps have several lighting modes you can choose from. Mostly by cycling through the modes, repeatedly pressing that one switch. A switch without proper feedback can easily get annoying.

Switch of the Cosmo pressed with a thick glove

The switch of the COSMO works very well. Even with thick gloves we can feel the switch and easily cycle through the modes. Always being in control.


The COSMO has two main lighting options. We can either use it’s bright Power LED in the middle, or two less bright LEDs on the sides. Besides that, it has strobe light mode and a red night vision mode. Last but not least there’s a locking mode to prevent the light from being turning on by accident.

New for us is the way how to adjust the brightness of the headlamp. Where other headlamps have click-through modes for different levels of brightness, the COSMO comes with a dimming function for it’s LEDs. Pushing the button once, turns the COSMO on. Holding the button, fluently dims the light down and up again – Until you release the button when the right brightness is found.

Well, why not? Yes, maybe a nice feature. Although it’s nothing we’ve been waiting for.

Main LED of the Cosmo burning
Side LEDs of the Cosmo burning
Red light of the Cosmo burning

The COSMO has quite a number of different lighting modes. Maybe too many, because we don’t see the specific advantages of the modes (besides the red light modes). Yes, the modes produce different light but none of them seems specifically designed for certain situations. For us, the two LEDs on the sides are almost useless. They are responsible for the strobe light, but every other light they produce can also be done with the main LED in the center.

What can get confusing, is cycling through the number of different modes with one button only. What’s easy looking at the headlamp, becomes quite confusing when you’re wearing it on your forehead. Then, you instantly lose control trying to find the right lighting or dimming mode.

APPLICATIONS (…or: what can I use it for?)

Now, BLACK DIAMOND is a manufacturer of outdoor equipment. So it’s pretty clear where they see their headlamps used. The COSMO they suggest for camping, climbing and light mountain sports.

We say, it has much more potential. Because it’s also the kind of headlamp for everyday use. For running, play, crafting or everything else around the house and the garden…

The Performance of the BLACK DIAMOND® COSMO

Let’s talk about performance. With most headlamps on the market (from various well known manufacturers) there’s a huge gap between what’s promised on the packagings and what you really get.

In some of our Blog entries we’re already (and in future) writing about how we’re measuring the performance of headlamps and why most manufacturers are massively cheating with their promises. If you’re interested in learning about this dirty game, please check these posts.

Now, lets see how the COSMO performed in our tests:

Cosmo packaging with printed specifications

The COSMO has two main lighting options. We can either use it’s bright Power LED in the middle, or two less bright LEDs on the sides. Besides that, it has strobe light mode and a red night vision mode. Last but not least there’s a locking mode to prevent the light from being turning on by accident.

What the Manufacturer promises and what we measure:

Power LED High: 90Lumen, 50 meter reach, 43 hours runtime (we measured: 34m, 4:30 hours)
Power LED Low: 4Lumen, 8 meter reach, 150 hours runtime (we measured: 5m, 153 hours)

2 Side LEDs High: 16 Lumen, 25 meter reach, 90 hours runtime (not interesting enough to measure)
2 Side LEDs Low: 4Lumen, 8 meter reach, 250 hours runtime (not interesting enough to measure)

Below the actual performance in diagrams:

Performance graph of Cosmo headlamp

The “end of light output” is reached, when 10% of the initial brightness are left. This rule is defined in the worldwide “FL1 Standard” for flashlights and headlamps.

You may not yet be aware of it. But headlamp beams shrink over time. A lamp with full batteries produces a full length beam. But the beam shortens as the batteries drain. So, the beams do not only get dimmer but also shorter over time.

Beam length of Cosmo headlamp

In the diagram above,  we calculated the length of the beams over time. For that calculation we used the standard formula of the worldwide “ANSI FL1 Standard”. According to that standard, the end of light output is reached when 10% of the initial brightness are left. Most manufacturers usually use their own rules for calculation, simply to make you believe their light would run much longer.


So, what’s our impression? Can we recommend the COSMO? So-so! The COSMO is definitely a very rugged “every day headlamp”. Not only for camping and light sports, but also for daily stuff around the house and the garden.

Over all we think the Cosmo is a very average headlamp. We mentioned before, we expected better from a manufacturer like BLACK DIAMOND. We expected more heart, more passion, better usability and better quality lenses. On the other hand side, we must not forget, the COSMO is an inexpensive headlamp, rugged enough to withstand everyday tasks. If that’s what you’re looking for, you’ll be a happy COSMO user.

We think it’s only natural that there are a few points of criticism. Most critical probably, the misleading specs of the manufacturer. Specifically regarding the battery runtimes. But we can tell you: Almost all manufacturers are playing the same game here. So, as long as you don’t believe in any of the claimed specs and rather check the actual performances above, you’ll be absolutely happy with your new COSMO.

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