It's designed specifically for rock climbing at night, but the Onsight 375 is actually good for all sorts of uses. Robust, weatherproof, easy to operate, and with a good balance of beam range versus battery life - all the factors that would make it a torch you might be glad of on a big wall in Yosemite are equally applicable to mountains in general. I think this would make an excellent main headtorch (always carry two) for the long nights and testing conditions of winter in the UK, whether you're climbing or hillwalking. Meanwhile this autumn, mine has been getting mileage as a night running torch - something for which it's also spot on.
The Onsight 375's main selling point is that it has two different light sources, which offer very distinct qualities of illumination. Switching between the two modes could not be simpler.
Separate light and rear-mounted battery pack vs all-in-one
For simplicity and packability I tend to favour all-in-one front-mounted headtorches, but they do have disadvantages versus an old fashioned two-part design. Spreading the weight between a rear-mounted battery pack and a front-mounted light unit can give a better-balanced feel than placing everything on the forehead, with less bounce when you're jogging along. This is clearly an advantage for running. On the other hand a torch with separate batteries is going to be bulkier overall, and more importantly may be more susceptible to damage than an all-in-one unit, thanks to the comparative vulnerability of the connecting wire.
With a rear batter pack, and a small front-mounted light, the Onsight 375 has the usual pros and cons of a two-piece model - but I think for this particular torch, the advantages of the design outweigh any drawbacks.
Weight and size
At 135g, including three AAA batteries, the Onsight 375 seems light for a two-part torch, and if I needed something reasonably powerful then I certainly wouldn't begrudge its weight and (minimal) bulk. Weight-wise it compares fine with other torches of similar output in Black Diamond's range: the Revolt 350 (an all-in-one model) at 90g; and the Storm 400 (all-in-one, but with four AAA batteries) at 120g.
Coming in two parts, this torch is inevitably less packable than a simpler one-piece model such as the Revolt, and the battery pack alone is bigger than most of my compact torches. Unlike them, it's not going to fit un-noticed in a pocket; however I would not call it bulky for a torch of this sort. Putting the batteries at the back has allowed Black Diamond to reduce the size of the light unit, making it thinner and less protruding than you'd expect on a model of similar output that carries everything up front. A less obtrusive light on your helmet is obviously something of an advantage when climbing, with the rock in your face.
In common with other current BD torches, the plastic housing and components all feel robust, and the whole thing seems well made. As for any torch with a separate battery pack, my main concern in terms of longevity would be the connecting wire, which is exposed to potential damage - even if your rough treatment amounts to no more than repeatedly stuffing it into a rucksack pocket. In the past, most such torches I've owned have eventually developed a loose connection at the wire. I can't say that this will never happen with the Onsight 375, but it doesn't seem as if it'd be easy to damage, since the point that the wire enters each unit is pretty sturdy. I'll have no qualms about using it as my primary torch this coming winter, a season that's generally tough on gear, and the time of year when reliability really is essential.
Two power sources can be used: either three standard AAAs, or the manufacturer's own BD 1800 Li-ion pack. The latter gives you ever so slightly more oomph and burn time, but it's sold separately, while the torch comes supplied with AAA cells. We didn't get a battery pack to review here, so I can't comment on its performance. I have subsequently replaced the non-rechargeable cells that came supplied, with a set of standard rechargeable AAAs.
Brightness and burn time
It's not aiming to compete in the lumens arms race, but with a top output of 375 lumens, the Onsight 375 (there's a clue in the name) has plenty of power for a torch of its fairly modest size and weight. Black Diamond's estimated maximum range of 88m with AAA batteries (110m with their own battery pack - not tested) seems about right, and on full beans, with freshly charged batteries, you can certainly see far enough to navigate complex ground on the hills, or negotiate a rough trail. I've taken it out walking at night, but though I've not yet used it for climbing after dark (a delight I try to forego, even in winter), it clearly has enough reach to pick out your next pitch, or the line of an abseil.
The light is dimmable. At medium power, 180 lm, you get a quoted range of 38m with AAA batteries, which I've found fine on more straightforward tracks. Minimum output of 8 lm takes you down to around 8m; let's call that camp mode since it's not much use for anything else.
According to the PDF of headlamp instructions, on full power a set of AAA batteries will give you 4.5 hours of juice (the product page on BD's website quotes different figures - go figure). My real world use suggests this is about right, if perhaps a bit ambitious. Medium output has a quoted 12 hour burn time - again, I'd say this sounds about right - while you can run at minimum for 72 hours.
The quoted operating temperature range between 43C and -17C would seem to have you covered for most scenarios except extreme cold. Of course all batteries suffer in the cold to one extent or another, and performance must vary a bit depending on what cells you put in. With this model there's no facility for keeping the power pack in a pocket, but that'll be no concern for UK use and only relevant if you're crossing the Greenland ice cap by pogo stick or some such. During the few months of this review mine hasn't faced serious double digit freezing, but it's fared well on cold evenings a bit below zero. To replicate more extreme use I tried a quick, non-rigorous home freezer test. After chilling for four hours at -20 the operation was unaffected, the light still bright, and battery life didn't seem seriously affected. Overall I'd consider this a good torch for winter use.
Many torches have a single fixed lens, while others might use some sort of focus mechanism to vary the beam from spot to flood. The Onsight 375, on the other hand, has two separate lights, and easily switches between two different beam configurations. With a simple pinch/tap to the housing the wearer can toggle between 'climb' mode, a soft wide-angle view for proximity work, and 'route-finding' setting, which adds a second brighter and more tightly-focused spot for distance vision. With its single light turned on (Climb mode) the maximum output is 300 lumens; add the second light and that goes up to 375 lumens, dramatically extending forward visibility. The quality of the beam is as much to do with the design of the lenses as the LEDs themselves.
The ability to very easily toggle between close-up and far-away is one of the features that's clearly designed to appeal to climbers, who will want to get a good all-round view of their immediate surroundings without being dazzled by their own glare on the rock, but also need to look further ahead to find the way. Off the crag and on the trail, I find the wide angle-only view a bit weedy and unfocused, and I do seem to prefer to stay in full-on spot mode most of the time, since it's never not useful to see further when you're walking at night. That said, I still think it's generally handy to have both options, not just for climbing but also for instance when hanging around in a tent. If you're saving battery life then the less powerful mode should still be sifficient to get you off the hill.
Being able to switch between the two beam patterns by simply pinching the light housing is pretty cool, and good news for winter is that it also works with gloves on (not just those designed to operate touch screens).
No night vision-preserving red mode is offered here, but as I've literally never used this (has anyone?) I can't say that bothers me.
Ease of use is one of my non-negotiables for any torch, and happily the Onsight 375 is suitably unfussy. A single button operates on/off, dimming, and switching between continuous beam and strobe mode. Hold the button down for a few seconds to lock it. A lock is of course essential on any torch for serious outdoor use, and while I suppose there's an outside chance that this one gets accidentally pressed in your pack, that doesn't seem likely. Though quite small, the button is usable wearing thick gloves.
A single wide elastic band gives a good close fit, with no need for a second overhead strap. To help keep things cool the headband is perforated, and though it's hard to be objective about a detail this small I do think this is one of the less sweaty headtorches I've used. The light mounting and battery case are both slightly contoured for a natural fit to the shape of your head (surprising how not all designs manage this), and the fact that the weight and bulk are split between front and rear really helps minimise any bounce or shifting around when you're moving. Overall the fit is comfy and secure.
To save craning your neck when looking at your feet, the head does the usual forward pivot; it may not tilt quite as far as many torches I've used, but that doesn't seem to matter in use.
With an IP67 rating, you can be confident that the Onsight 375 is fully waterproof - not just shower resistant, but actually submersible. In fact it's made to go on working for 30 minutes in up to 1m of water, and that should even cover you for a damp day in Cumbria. Out on the hills in all weathers, the last thing you want is for your torch to pack up in the wet. Being waterproof is good for peace of mind, and yet another reason to choose this model as your winter workhorse.
While it's marketed as a model for multi pitch climbing in the dark, the Onsight 375 would shine in a lot more situations than this one quite specialist use. Tough, weather-proof, and comfortable on the head, it gets all the basics right, while the sensible balance between output and battery life makes it a good option for hillwalking and winter climbing. The ability to flick between close-up and long-distance modes is also really good.
Black Diamond say:
The Onsight is our purpose-built solution for climbers seeking additional climb time after the sun has set. A climber's desire for simplicity and robustness were built into every aspect of this light from the single button architecture to its fully submersible IP67 waterproof construction. You'll first notice the Onsight's dual-beam configuration, which provides the two main lighting modes climbers need most. The main Climbing Mode was optimized for illuminating the holds or trail directly in front of you with 300 lumens of wide evenly dispersed light that doesn't glare when you're looking for the next crimper or small foothold. The secondary Route-Finder Mode adds a powerful, narrow, long-distance beam and increases the total max output to 375 lumens allowing you to spot anchors or search for trails off in the distance.
- Weight: 135g with batteries
- Lumens: 375
- Max Burntime: FL1 3 H; reserve 26 H (highest setting) 100 H (lowest setting)
- Max Distance: (High) 85m, (Low) 8m
- Dual-beam configuration, providing the two main lighting modes climbers need most: Climbing Mode and Route-Finding Mode
- Climbing Mode illuminates the holds or trail directly in front of you with 300 lumens of wide evenly dispersed light
- Route-Finder Mode adds a powerful, narrow, long-distance beam and increases the total max output to 375 lumens
- Dual PowerTap™ technology easily toggles between Climbing and Route-Finder Modes by touching both the right and left side of the front housing
- Dual-Fuel: Maximum flexibility to utilize either the rechargeable Lithium Ion BD 1800 battery or 3x AAA Alkaline cells (Alkaline batteries included, Lithium Ion BD 1800 battery sold separately)
- Ultra-thin front housing with extra articulation
- Perforated elastic headband for breathability and lightweight performance
- Six-setting 3 LED battery meter
- Brightness Memory allows you to turn the light on and off at a chosen brightness without reverting back to full or mid-power
- Digital lockout feature safeguards against accidental use when stored in a pack or pocket
- IPX Rating: IP 67