A few Surefire A2 pics.

[J-sews]

yep... i just checked to make sure.

Don't you trust me then? 

i don't trust me. 

Ooooh, good save man - his finger was hovering over The Button!

[Mike, Lord of the Spammers!]

So instead of lumens, what should us Jamie newb's be looking for when assessing performance 

[Benner]

So instead of lumens, what should us Jamie newb's be looking for when assessing performance 

Ideally you want measurements of throw/ spill and beamshots.  But it really depends on what you want out of your light.

[Mike, Lord of the Spammers!]

So instead of lumens, what should us Jamie newb's be looking for when assessing performance 

Ideally you want measurements of throw/ spill and beamshots.  But it really depends on what you want out of your light.

And naturally the manufactures don't really list those

[ringzero]

So instead of lumens, what should us Jamie newb's be looking for when assessing performance  

LUMEN output is useful because it is a measure of the total light pumped out by the torch.

LUX measurement is useful because it is the intensity of the brightest part of the torch's beam.  LUX measurement can be used to predict how far the torch will throw a useful beam.

Example:

20 Lumens is approximately the output of a cheap, plastic 2D supermarket incandescent torch with fresh cells.

Such a torch might produce 900 Lux in the center of its beam.

Take the square root of 900 to get 30.

This is the distance in meters at which the torch will put 1 Lumen of light on a 1 meter sqaure target.

If your eyes were totally dark adapted and you were in a dark wildnerness scenario, then that 1 Lumen per meter squared might be a useful amount of light.

In an urban scenario (streetlights, porchlights, etc.) that 1 Lumen/m2 would probably be useless to see anything.

Derate that 30 meter distance by half to 15 meters.  This is the aprroximate distance at which a 20 Lumen, 900 Lux torch would usefully illluminate a target in an urban scenario.

In other words, for use around town, a 2D incan supermarket torch is predicted by its Lux measurement to be useful out to about 50 feet.  Out in the dark woods, the same light might be useful out to about 100 feet.

Both of these numbers seem to fit well with the experiential reality of using such a torch, so the mathematical model is fairly good.

Summary:

Take the square root of the Lux measurment, which gives the useful throw in meters for a wilderness scenario.

Divide that by two for an urban scenario, which gives the useful throw in meters for urban use.

If you wish, multiply the throw in meters by three to get throw in feet.

.

[Benner]

So instead of lumens, what should us Jamie newb's be looking for when assessing performance 

Ideally you want measurements of throw/ spill and beamshots.  But it really depends on what you want out of your light.

And naturally the manufactures don't really list those

They are easily found though.  flashlightreviews.com is a good site for example.

[ringzero]

So instead of lumens, what should us Jamie newb's be looking for when assessing performance 

Ideally you want measurements of throw/ spill and beamshots.  But it really depends on what you want out of your light.

And naturally the manufactures don't really list those

They are easily found though.  flashlightreviews.com is a good site for example.

Quality manufacturers will usually quote both Lumens and Lux for a given model.

Some manufacturers will give Lux, but not Lumens.

This is because it's quite easy to measure Lux with very simple equipment.

An accurate Lumens measurement is harder to get, requiring a specialized piece of equipment known as an integrating sphere.

.

[prime77]

They are easily found though.  flashlightreviews.com is a good site for example.

Be warned about flashlightreviews.com though. The original owner of the site Quickbeam from CPF sold the domain to new owners but not all the content and reviews that he did. Then the new owners put all his reviews up. And have has been copying reviews from other sites most notably lightreviews.com.

[Mike, Lord of the Spammers!]

So instead of lumens, what should us Jamie newb's be looking for when assessing performance  

LUMEN output is useful because it is a measure of the total light pumped out by the torch.

LUX measurement is useful because it is the intensity of the brightest part of the torch's beam.  LUX measurement can be used to predict how far the torch will throw a useful beam.

Example:

20 Lumens is approximately the output of a cheap, plastic 2D supermarket incandescent torch with fresh cells.

Such a torch might produce 900 Lux in the center of its beam.

Take the square root of 900 to get 30.

This is the distance in meters at which the torch will put 1 Lumen of light on a 1 meter sqaure target.

If your eyes were totally dark adapted and you were in a dark wildnerness scenario, then that 1 Lumen per meter squared might be a useful amount of light.

In an urban scenario (streetlights, porchlights, etc.) that 1 Lumen/m2 would probably be useless to see anything.

Derate that 30 meter distance by half to 15 meters.  This is the aprroximate distance at which a 20 Lumen, 900 Lux torch would usefully illluminate a target in an urban scenario.

In other words, for use around town, a 2D incan supermarket torch is predicted by its Lux measurement to be useful out to about 50 feet.  Out in the dark woods, the same light might be useful out to about 100 feet.

Both of these numbers seem to fit well with the experiential reality of using such a torch, so the mathematical model is fairly good.

Summary:

Take the square root of the Lux measurment, which gives the useful throw in meters for a wilderness scenario.

Divide that by two for an urban scenario, which gives the useful throw in meters for urban use.

If you wish, multiply the throw in meters by three to get throw in feet.

.

I think I've got it now

Thanks for the explanation mate

[Magic Bus]

I wonder how one of these stacks up against the Nitecore DI? 

[Benner]

I wonder how one of these stacks up against the Nitecore DI? 

LED output wise, the Nitecore will pi$$ all over it as the A2's LED's are meant for close up work and offer a lot of spill and nigh on no throw whatsoever.  Switch to incan though, and throw wise that's where the Nitecore would struggle I expect.

[Magic Bus]

I wonder how one of these stacks up against the Nitecore DI? 

LED output wise, the Nitecore will pi$$ all over it as the A2's LED's are meant for close up work and offer a lot of spill and nigh on no throw whatsoever.  Switch to incan though, and throw wise that's where the Nitecore would struggle I expect.

Thanks Ben. The SF looks very nice, but it's out of my league at the moment. I have read about the DI though and it sounds pretty good.

[Benner]

The reason I went with the A2 is because I am colourblind and found that LED's outside made everything look flat and kind of greyscale.  Problem is, incans eat batteries so I ideally wanted a torch where I could have LED's for inside and incan for out so I could have the better run time.  This obviously fitted the bill perfectly.

[Magic Bus]

The reason I went with the A2 is because I am colourblind and found that LED's outside made everything look flat and kind of greyscale.  Problem is, incans eat batteries so I ideally wanted a torch where I could have LED's for inside and incan for out so I could have the better run time.  This obviously fitted the bill perfectly.

Can't fault your logic  I wonder how robust the incan bulb is? I take it it's got to be better than a Maglite incan bulb 

[Benner]

The reason I went with the A2 is because I am colourblind and found that LED's outside made everything look flat and kind of greyscale.  Problem is, incans eat batteries so I ideally wanted a torch where I could have LED's for inside and incan for out so I could have the better run time.  This obviously fitted the bill perfectly.

Can't fault your logic  I wonder how robust the incan bulb is? I take it it's got to be better than a Maglite incan bulb 

The bulbs are very well protected from shocks.  Still easily breakable though I expect.

[Magic Bus]

I hope bet you'll enjoy it 

[Benner]

Well after carrying this light for nigh on every day for the last 7 months, I finally had to change the batteries today.  The batteries that came with it weren't even new when I got it and I only replaced them today because I had lost incan function - the LED's still worked as normal.

So for those who doubt the cost effectiveness of CR123 cells, I reckon 8 months ish for $3 is great value. 

[Mike, Lord of the Spammers!]

That's pretty impressive mate

[ryan1835]

  that is how much did you pay for the light?

[Benner]

Can't remember now.  Got it used from the US and then upgraded the bulb to a HO Lumens factory one.  All in I believe it was in the £70's.

[ryan1835]

not like the £200 on heinnie s then

[Benner]

Nowhere near. 

Got batteries and the lanyard in that price as well.

[ryan1835]

might have to do a bit of looking then

[Black Rose]

Can't remember now.  Got it used from the US and then upgraded the bulb to a HO Lumens factory one.  All in I believe it was in the £70's.

Not a bad price at all. 

[NutSAK]

How many spare bulbs do you incan users carry?

[Benner]

I don't carry any spares.

[ryan1835]

what does incan mean?

sorry to go off topic

[NutSAK]

what does incan mean?

sorry to go off topic

It's not really off topic, since the A2 is partially incan.

incan=incandescent  The high output mode emits from an incandescent bulb rather than an LED.

[NutSAK]

I don't carry any spares.

How many hours is the £70 bulb good for?

[ryan1835]

what does incan mean?

sorry to go off topic

It's not really off topic, since the A2 is partially incan.

incan=incandescent  The high output mode emits from an incandescent bulb rather than an LED.

oh so it has a bulb and an led?