Handheld Primary Light (Cave)

[RyanT]

I run it on power setting 2 because power setting 1 is just too bright for me.

Your eyes are probably better than mine, I sure like my LX20+ on high!

 

[inquis]

Why the LX20+ instead of the Dive Rite HP50?

I use the LX20+ as well. Primary considerations for my decision were the smaller beam angle (brighter spot, 20% more lux based on specs) and constant-current driver (stable brightness). Longer runtime on high and lower price also favor the LX20+.

 

[stuartv]

I use the LX20+ as well. Primary considerations for my decision were the smaller beam angle (brighter spot, 20% more lux based on specs)

I'm surprised by that. I know it's 10 degrees versus 6. But, it's also 3500 lumens versus 1500. I still would have thought the HP50 had a brighter, as well as bigger, spot.

and constant-current driver (stable brightness). Longer runtime on high and lower price also favor the LX20+.

The LX20+ is 1500 on High. Why compare runtime on High instead of runtime when putting out 1500 lumens? It looked to me (my guess) that the HP50 would have a longer runtime when running at approximately the same brightness as the LX20+.

I couldn't find any info on whether either light stays the same brightness or gradually dims.

As the Dive Rite EX35 gradually dims, I figured the LX20+ and the HP50 would both work the same.

Do you happen to recall where you found info that the LX20+ stays the same brightness all the way until it goes into low power mode? (I'm inferring that's what you meant by "constant-current driver")

 

[inquis]

I'm surprised by that. I know it's 10 degrees versus 6. But, it's also 3500 lumens versus 1500.

You've not alone, but the reason is an inverse-squared dependency on spot diameter.

Why compare runtime on High instead of runtime when putting out 1500 lumens? It looked to me (my guess) that the HP50 would have a longer runtime when running at approximately the same brightness as the LX20+.

Your guess is based on diameter rather than area, which leads to a faulty conclusion. High on HP50 is as close to the same lumens per area as it can get.

 

[inquis]

Do you happen to recall where you found info that the LX20+ stays the same brightness all the way until it goes into low power mode?

From Dive Rite:

A true constant current LED driver provides unparalleled efficiency and ensures constant light output as the battery is depleted.

My last burn test gave 2:45 on high (stock batteries) before stepping down.

 

[stuartv]

From Dive Rite:

My last burn test gave 2:45 on high (stock batteries) before stepping down.

I'll be dipped! I skimmed right over that. Thank you!!

 

[stuartv]

From Dive Rite:

My last burn test gave 2:45 on high (stock batteries) before stepping down.

Any thoughts on why it gets 2:45 at 1500 lumens, but they say it only gets 3:00 at 750 lumens?

I would have thought burn time at half the output would be at least double.

 

[inquis]

I would have thought burn time at half the output would be at least double.

Yeah, the spec of 2:15 vs 3 hr doesn't make sense to me either. Certainly it will go past 3 on Med, but I haven't quantified how far.

 

[Capt Jim Wyatt]

Just curious. Why the LX20+ instead of the Dive Rite HP50?

I think there was no HP50 when I got my LX20+ ??

Your eyes are probably better than mine, I sure like my LX20+ on high!

In a huge passageway I like it on bright, but normally I am just fine on setting #2.

 

[tbone1004]

That is great analysis (as I generally expect from you, of course). Thank you!

You hit the nail on the head on the bottom line: My shop is a dealer. I am getting it at dealer cost. It's not part of the uniform, per se, but all the shop staff except me do use them. And, enough people that I know use them for cave diving that I want to try it out.

If there was a MIA light that was good as a spot beam for caves and also switchable to a good flood for video, all in one light, and I could get it at dealer cost, I would definitely want to try it! As it is now, the only MIA video lights I know of are UWLD and the 10K lm is way out of my price range and the 5K is also out of my price range and it's not cordless (which I do want).

The Light & Motion lights are made here, so are Dive Rite's. The issue is getting flood and spot in the same light, most people don't do that for a reason....

HP50 vs LX20 is a beam angle thing. LX is 6*, HP50 is 10. 10 is a pretty useless beam angle IMO for most of the Florida cave systems. Too wide with the amount of particulate in the water but not wide enough for video.

Also, regarding lumens, and I'm talking real lumens like those quoted by companies like UWLD, Dive Rite, Light and Motion etc. with constant output drivers vs. bullsh!t claims about theoretical lumens like BB, Orcatorch, etc. I grew up in cave diving right as LED's were coming out where 10w HID's were the norm, those were about 700-800 lumen. @Capt Jim Wyatt grew up in the dark ages, almost literally where 200-300 lumens were a lot in the incandescent days so while I may own a pair of UWLD LD-40's and very much enjoy that amount of light, it is not unheard of for me when teaching to use backup lights on a goodman sock and even when diving with newer divers to just grab a backup light in the 700-800 lumen range or use my LX20+ on low or medium which is truly more than enough light for what you need. It gives you a completely different perspective on the cave