Can you "see" 20 lumens?

I recently bought the Solarforce Skyline I (there was a really good deal on eBay).

According to measurements by BigChelis the Skyline I will put out about 145 lumens using 2 x CR123 and about 125 lumens using 1 x 18650.

I don't have any CR123 batteries - is it worth buying some for the sake of 20 lumens? Bearing in mind this is a thrower, would I even notice the difference if I'm standing 100 feet away from what I'm pointing at?

I'd like to use 2 x 16340 but this isn't recommended because it goes over the 6V limit of the LED.

All advice gratefully accepted.

the difference will be very small. I would go for the 18650, since they are rechargeable.
one 18650 battery also has a much bigger capacity than two 16340 batteries.

You would notice it in the same way you would notice 145 mouth-fulls of ice cream as opposed to 125 mouth-fulls of ice cream.

As said, an 18650 will give you 125 mouth-fulls for longer (low GI ice cream).

Jash said:

You would notice it in the same way you would notice 145 mouth-fulls of ice cream as opposed to 125 mouth-fulls of ice cream.

As said, an 18650 will give you 125 mouth-fulls for longer (low GI ice cream).

Click to expand...

Great analogy? Or greatest analogy ever?

More on topic, the eye sees on a roughly logarithmic scale. This means a 20 lumen difference between 20 and 40 would seem much bigger than a 20 lumen difference between 125 and 145. Someone posted a great graph and chart a while ago of this. I wish I could find it.

Helmut.G and Jash - many thanks for your answers. Seems like it's not worth shelling out for 2 x CR123.

I'm already using an 18650.

The reason I mentioned 2 x 16340 was that if 2 x CR123(which I do not own) gives more lumens then my assumption was so should 2 x 16340 (which I do own) , and since they are rechargeable I would be getting guilt-free lumens.

Now I'm off to the freezer to do some serious ice cream consumption.

hello Vasp1 --


I have a flashlight, which puts out (OTF)

Medium: 60 Lumens

High: 160 Lumens


I just about ALWAYS use it on Medium, because the jump to High
simply doesn't seem like that much more light output !

And, of course, gives me Much longer run-time, ta' boot !


If i hadn't experienced this fact for Myself, i probably wouldn't have believed it.


Stick with yer' 18650 battery, and Be Happy !

:thumbsup:

_

Yeah, what he said.

With the Skyline, DO NOT USE 2x16340

It's rated for a max of 6v input. You can use 2xCR123 or 1x18650, that's all.

I have one of these, and the difference between 2xCR123 and 1X18650 is negligible.

Stick to your 18650.

Realistically, no, you can't see 20 lumens on top of 125 lumens. (You can, however, see 5 vs 25 lumens very very easily).

Also, 18650 will provide far better runtime

Well, at 125 lumens the light will be useful out to a certain distance.

At 145 lumens it will be useful out to a slightly further distance.

If you're at 125 lumens and what you're trying to see happens to be a few feet outside your current range, well then you're definitely going to notice that 20 lumens.

The real question though is how often would you end up in that kind of a "hair splitting" scenario?

lunchboxtheman said:

the eye sees on a roughly logarithmic scale. This means a 20 lumen difference between 20 and 40 would seem much bigger than a 20 lumen difference between 125 and 145. Someone posted a great graph and chart a while ago of this. I wish I could find it.

Click to expand...

"Perceived Brightness Index"
https://www.candlepowerforums.com/threads/271967

Jash said:

You would notice it in the same way you would notice 145 mouth-fulls of ice cream as opposed to 125 mouth-fulls of ice cream.

As said, an 18650 will give you 125 mouth-fulls for longer (low GI ice cream).

Click to expand...

Thanks for the laugh!!!

Seriously, as everyone's said above, use your 18650's all you can, the lumens difference will be minimal. Also, unless you have a bunch of 18650's fully charged as backups, I would buy a pair of CR123's, put them in a memorable place, and know they're there just in case. It's never bad to have a set of backup primaries stashed away.

Flint&Steel said:

Thanks for the laugh!!!

Seriously, as everyone's said above, use your 18650's all you can, the lumens difference will be minimal. Also, unless you have a bunch of 18650's fully charged as backups, I would buy a pair of CR123's, put them in a memorable place, and know they're there just in case. It's never bad to have a set of backup primaries stashed away.

Click to expand...

Yes to this it's a good idea to still keep a stash of primaries incase you should need them. I'd say two to four in each vehicle and a few at home.

Thank you one and all for your advice. lovecpf

Vasp...I have the skyline, and I think the difference between the two batteries is definitely enough to gets some primaries. It depends of course of what you are doing...but the 2 123's will do better...because the skyline concentrates the light so much, that the small difference shows up more than a regular light.

By the way, the factory made a mistake and sent my light with 2 RCR 123 batteries inside the light. I suspect they test the lights with these and forgot to remove them. Yes, I used them and they work great. I've have since switched to primaries since the factory does not recommend them. I suspect this is just a precaution on their part.

lunchboxtheman said:

Great analogy? Or greatest analogy ever?

Click to expand...

It's pretty good, but for the life of me I cant stop thinking about the awful brain freeze after 145 mouth-fulls of ice cream long enough to apply it to output. :sick2:

I have a Ra Clicky EDC120, and it steps down from 120 to 85 lumens after 10 seconds. (35 lumens) I have missed the transition more than once, especially when the beam is moving. As has been said, stick to the 18650's.

scout24 said:

I have a Ra Clicky EDC120, and it steps down from 120 to 85 lumens after 10 seconds. (35 lumens) I have missed the transition more than once, especially when the beam is moving. As has been said, stick to the 18650's.

Click to expand...

Along those lines, my Clicky 170 steps down from my measured 160 to 110 - 50 lumens - and I can barely see it. I have to literally watch for it.

Just supporting what everyone else has said...

:wave:

I am going to say the only way you are going to see 20 lumens is on a graph or in a test lab, not in the real world.

Jash said:

You would notice it in the same way you would notice 145 mouth-fulls of ice cream as opposed to 125 mouth-fulls of ice cream.

As said, an 18650 will give you 125 mouth-fulls for longer (low GI ice cream).

Click to expand...

Best. Answer. Ever,

Succinct and illustrative.