I have built my own lights. I also have the HP50.
I echo nearly everything
@tbone1004 said. I built my own LED light from an old DR HID about 10 years ago. It kicked the butt of any LED you could buy at the time: Crazy Lumens (like brighter than lights that claim 3000 lumens), 10 hour life, awesome LED driver with all kinds of cool features (cutter.com.au). I spent about $400 converting it. Two problems: the battery canister was huge (an old MLS-1) and the light spread quite wide. (It’s actually great in wrecks! But not so much caves.) A different canister would have driven up the cost (and shrunk battery life). Coming up with better optics for the LED would have been difficult and likely expensive.
That was 10 years ago. Today, the commercial lights have caught up, and DIY costs have increased. LiPo/LiFe batteries and chargers cost a lot more than the NiMH I used; and the engineering to do them “right” (including in a travel-compatible way) is much harder, too. Do it for entertainment? OK. But know going in you’ll spend more and get less than just buying a commercial light.
So, given all of that, I bought the HP50 last January. I bought the expedition canister for the battery life. The canister is slim, and the light head is decently-sized, and I really like the QR system (with a couple of complaints, too). I went with the HP50 because at the time they were the only one using that LED, and I paid a couple hundred below list (less than $1000), so it was the best combination of price and capability. I figured within 18 months I’d have a lot to choose from, but I didn’t want to wait.
The light is plenty bright. But compared to the LM and UWLD lights I saw in the caves recently, it’s not really brighter, despite the newer LED. (Light response of the eye is non-linear: it takes much more than twice as many lumens to seem ‘twice’ as bright.) It is noticeably less spotty: to the point I’ve thought about monkeying with a collimating lens... which means it has the same problem as my old one! Not as bad, but I understand why 8 degrees or less would be nice, too.
As for whether the light uses a constant-output driver or not, I’m not sure that’s accurate. I’m not saying
@tbone1004 is wrong, I'm just not sure he’s right! I know my BX2 light does not, but I thought the HP50 did. In any case, I can say 2 things: 1) I have not noticed a dropoff in light output over its burn time, and 2) it *will* step down the output when battery levels require. And it will step down earlier than I thought it would, given the battery capacity. I’ve never calculated it exactly, but I think it’s probably like 250 or less minutes on high before step down—nothing anywhere near 10 hours... Long enough for me, but less than I expected. And the step down level is decently bright.
As for overdriving: I’m fine with that. Even 20% life expectancy would be 10,000 hours. If I got 10,000 hours under the water before the batteries wear out I’d be shocked. Literally thousands of multi-hour dives! And seeing as a new canister is over half the cost of a new light... it would mean a whole new light for me anyway. So I’d rather use up that LED with more brightness anyway!
I mentioned the BX2. The two make a decent pair: I can use the BX2 as my backup and simply clip it on my handle. Real nice system in my limited experience so far.
So to sum up: the HP50 is a decent value as part of a light system, including QR and backup working together. But not the “best”, pretty much no matter how you measure. There are cheaper Chinese lights, and there are more expensive LM and UWLD lights.
Oh, one thing I can’t stand: the stupid Hall effect switch. It sticks, and it’s big. (DR needs to do more dives in sand for testing...) Why, oh why could they not use a piezo like EVERYBODY ELSE?!? Ok, it’s not that big a deal, but c’mon, it’s a brave new world, DR...
Anyway, let me know if you have any questions about the HP50.
