# HDS Systems #23

#### desert.snake

##### Flashlight Enthusiast
We just need to wait a bit for the output of 3V LED with 1000 lm / W and everything will be fine

#### Slumber

##### Flashlight Enthusiast
Henry has minimum runtime requirements. I believe that is one of the major reasons he doesn't build hot rod lights along with all the other benefits of not driving them harder.

#### Hogokansatsukan

##### Flashlight Enthusiast
1000 lumens isn't that big a step from 325 from what your eyes perceive. While it sounds like 3X the output and technically is, your eyes will NOT perceive it as being that. One of the reasons we always hear folks who buy their first HDS say "it's a lot brighter than I thought it would be." The other reason is, of course, we don't fib about the output.
From the FAQ
What is the logarithmic nature of my eyes?

Your eyes respond to light in a logarithmic way. That means they require a significant percentage change in light output for your eyes to notice a small but visible change in brightness. A 50% (1.5x) increase or 33% (0.67x) decrease will produce a small but visible change in brightness. An increase or decrease of half that - 25% (1.25x) and 20% (0.80x) respectively - will probably not be noticed.
You are probably already familiar with logarithmic scales in other areas of your life. For instance, earthquakes are measured using the logarithmic Richter scale. Sound is measured in logarithmic decibels. If you are a photographer, you are familier with the logarithmic f-stops and the logarithmic progression of shutter speeds. Even the musical notes in an equal temperament scale are logarithmically spaced. Logarithmic scales make it much easier to represent very large variations from tiny to huge because the scale represents a progression of ratios instead of a progression of linear units. The perception of most physical phenomena by our bodies - sight, sound and touch - are essentially logarithmic. It is difficult for us to perceive small percentage changes.
Many people are surprised to find out that going from 0.17 to 0.25 lumens looks the same as going from 167 to 250 lumens. From your eye's perspective, the step size is the same in both cases - a small but visible change. Notice that in the first case we only increased by 0.08 lumens while in the second case we increased by 83 lumens - a difference of 3 orders of magnitude.
You might be surprised to find out that you need a 10x increase in light to produce what most people consider to be a doubling in the amount of light. Again, this is due to the logarithmic nature of your eyes.

#### tech25

##### Flashlight Enthusiast
One of the reasons we always hear folks who buy their first HDS say "it's a lot brighter than I thought it would be."
I’m one of those.

#### ilikeguns40

##### Enlightened
Plenty bright for my needs considering 50 lumens and under is 90% of my usage

#### kaichu dento

##### Flashaholic
I'll say that I'm one of the owners who has always wished for Boss 35 brightness from an HDS, but also understand why we'll never get it. I may seldom need more than what my Rotary puts out, but when I do, it would be nice to have it. Anyway, the Rotary is still one of my favorite lights ever, and the only one that has never taken a break from daily carry, even if it's been my backup light for the past month or so.

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#### Mgizler

##### Enlightened
I will admit, Its hard to not buy into the lumen race…..but……every time I do, I realize that I just don’t need that much light. Or I realize that it’s a crazy amount of light for a very short period of time. And I end up using a brightness that any hds I own can handle.

Now onto the hds brightness side of things…… I have had the 120, 170, still have a 200 and a 250. Every single one of them had enough light and throw to make them look just like higher lumen lights that I have had and still own. Like said above…..more often than not, someone will buy an hds, or try one and think…..wow that’s brighter than I thought it would be.

I have gone away and come back around to hds many times over. This time it has lasted the longest. And I have no reason to get rid of them.

Yes they are getting more and more expensive every day. But so is everything else in our lives. But at least with an hds I know it was hand built by hard working people, and it will last a lifetime!

Before anyone counts one out…. You must give it a try…..I can guarantee that carrying/using one for a few days straight will change your mind!!

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#### kerneldrop

##### Flashlight Enthusiast
My only hang up with the rotary is you gotta turn all the way to level 19 to get above 20 lumens.

I know, I know… 2.44 HDS lumens at level 13 is enough for us hardusers.

I’m in the executive camp

#### ilikeguns40

##### Enlightened
Executive is where it’s at for me

#### Mgizler

##### Enlightened
My only hang up with the rotary is you gotta turn all the way to level 19 to get above 20 lumens.

I know, I know… 2.44 HDS lumens at level 13 is enough for us hardusers.

I’m in the executive camp
I get that. And I can also see how it seems like there are a lot of wasted levels. I I do love, my executive clicky, but the rotary knob is unbelievable for a quick operation from low to medium to high brightness. I think the answer is to just have both. And carry them at the same time. Yep I’m gonna go with that.

#### cerbie

##### Enlightened
My only hang up with the rotary is you gotta turn all the way to level 19 to get above 20 lumens.

I know, I know… 2.44 HDS lumens at level 13 is enough for us hardusers.

I’m in the executive camp
That's why my rotaries are Tactical. They would be improved by a detent prior to going momentary, but I like the reduced twisting all the same.

My EDC is a clicky, though. Even with a protruding button, the shaft-wise movement of the tailcap gets in the way of being able to reliably and reflexively multi-click, IME, even though the same options are there. So, I treat my rotaries as just having on/off/burst.

Being able to dial in the output over time is nice, but for for just whipping the light out and using it, for a short period of time, coarser control is just fine, faster, and easier. It's long since become muscle memory, and doesn't require any changing grips. As well, I find the sloped tube to tailcap section on a Clicky CR123 body to be more comfortable to hold in a cigar/pencil grip, rather than the rotary knob edge.

For nighttime walking or hiking (am night owl), my 18650 Tactical (High Noon, but that's not terribly relevant), with a smooth reflector, is amazing, still, and has probably saved me more money over these last several years, in other lights I chose not to buy, than it cost (I'm not a headlamp fan). I can keep the output low enough to maintain some degree of dark adapted vision (the level of which varies by where I am, and the state of clouds and the moon), then twist it brighter to look farther away, and back down as I use again just to see where I'm going. The 18650 size is more comfortable, to me, anyway, to hold in a grip where I keep the rotary knob near the base of my hand, ready to use, though too big for comfy EDC.

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#### kerneldrop

##### Flashlight Enthusiast
What can be seen by .02 lumen?
Steps 1-5 range from .02 - .10 lumen…does anyone use those steps?

#### Commodorefirst

##### Newly Enlightened
What can be seen by .02 lumen?
Steps 1-5 range from .02 - .10 lumen…does anyone use those steps?
Yes, all the time during our power outages, turn it on step 2, 3, 4 and leave it on in the room I am in, also at night outdoors in a blind when dark adapted, although I like my red nest for that.

#### Duster1671

##### Enlightened
The single emitter/deep reflector design matters too. 300 Lumens out of an HDS, Malkoff, Zebralight, Haiku, etc. is a lot more useful than 300 lumens out of a triple/quad emitter/TIR light.

#### jonathannnc

##### Enlightened
The single emitter/deep reflector design matters too. 300 Lumens out of an HDS, Malkoff, Zebralight, Haiku, etc. is a lot more useful than 300 lumens out of a triple/quad emitter/TIR light.
Completely agree.

#### ironhorse

##### Enlightened
The lowest level is enough light to get around in the middle of the night.

#### Showngo

##### Newly Enlightened
The lowest level is enough light to get around in the middle of the night.
Sometimes it is too much light

#### kerneldrop

##### Flashlight Enthusiast
Sometimes it is too much light
Haha, exactly. I use a Jetbeam RRT01 rotary when I need less than .02 lumen

#### Slumber

##### Flashlight Enthusiast
Those sub-lumen levels seem to be getting less and less useful the older I get. These days I mostly use turn on preset or max on my Clickys which is why a rotary would be wasted on me.