pc_light
Enlightened
I was in the market for a new headlamp so I decided to pick up the FourSevens Atom AL, the idea of a headlamp that could be quickly removed for use as a handheld sounded promising. Never having owned a mule I wasn't sure what to expect. With a reflector flashlight, the Atom AL's (cr123a) spec of 110 lumens on High should have been plenty. I was not prepared for reality with the Atom which was a little different.
On High I found the Atom AL acceptably bright for most tasks, a little more punch would have been fine too. The Low setting, on the other hand was limited to use during pitch blackness and/or for slowly moving about. Runtimes of 3-3.5 hours of flat regulated output on High using a primary (more using a rechargeable) and days of regulated output on Low was GREAT though.
The main problem wasn't light output, it was the excessively broad spill of the mule that frankly wasted a lot of light for my needs. I didn't need the upward lighting, nor the super wide left and right that was beyond my personal field-of-view, and worst was directed into the eyes of people who might be facing my general direction.Perhaps others had the same experience which was why FourSevens subsequently came out with the special reflectored model of Atoms, so I picked up an Atom AAF (an Atom AA with reflector), to try. To my disappointment, the special low profile reflector chosen for the Atom looked and projected just like my Quark Mini-AA. Still there's no point in living with a light that doesn't meet your needs, just move-it-out or mod-it-up, that's the CPF way!
I needed a beam half way between a hotspot reflector and the overly wide mule, perhaps an optic. But most optics are still too narrow or have funny beam patterns. I decided to try a plane convex (speherical) lens, like those found on inexpensive zoomies. As there was no off-the-shelf lens I could drop into the light, I got one sized as close as I could then sanded it down to fit into the Atom.
So, with the stock Atom AL as a control and the Atom AAF retrofitted with a convex lens, I made some comparisons of their relative brightness. The photos below show the results of putting a simple convex lens into the Atom.
Some background details to put the results in context.
-------------------------------------------------------------
The Atom AL (w/cr123a) (on left oem Mule)
- High = 110 Lumens
- Low = 6 lumens
The Atom AA (AA w/alkaline) (on right w/convex lens)
- High = 70 Lumens
- Low = 1.5 lumens
(Since I had the lights opened, I swapped the cool XP-G2's with a Hi-CRI Nichia 219b and 219c (4000K) as a bonus
)
Atom AL mule on low @6 Lumens (left) vs Atom AA+lens on low @1.5 lumens (right) -
(due to the wide nature of mule beams, lights were only 6-inches from wall)
The photos don't show the full extent of the AL mule spill but the area is many times that of the lensed AA+ light. Yet, the illuminated areas of the lights have similar levels of intensity even though one light is supposedly outputting 4X the lumens (6 vs 1.5 lm) of the other.
When both lights are on High the illuminated portion of the 110-lumen AL mule (left) appears no brighter (actually less) than the 70-lumen AA+ (on right). The difference in person was greater than what may be evident in the photo.
Here is a profile of the beams showing the relative angles and thus the respective area being illuminated.
The AL in it's original form is spec'd as 120° (left), whereas the AA with lens (right) is now reduced to about 70°.
What's Going 'On?
--------------------
Basic geometry indicates that the area created by a 120° projection is 6X that of the area created by a 70° projection. Assuming this relationship transfers directly to the math involved with calculating area illumination, "harnessing" the light that was previously spread over the wider area should be 6X brighter when the same lumens are focused down to the reduced area created by the narrower lens beam (increased lux) . The photos (2 prior) of the AL (120°) vs the AF+ (70°) seem to bear this out, with the higher output AL (6 lm) appearing no brighter (actually less) than the lower output AF+ (1.5 lm) in the illuminated areas.
Results of adding a simple convex lens to The Atom AA mule
------------------------------------------------------------------------
GAINS -
- the illuminated portions on High now appear brighter
- the Low is brighter and more useable for my purposes, and
- the narrower angle means I no longer inadvetantly shine at people in my peripheral.
LOSSES -
- a smaller overall area being illuminated,
- the loss of a low moonlight mode,
- loss of some water tightness as my lens was hand-filed and not perfectly round (a small lathe would have useful).
- ability to stand either end, tail only now due to bump out from convex lens
On balance, I like the brighter narrower, but by no means narrow, light produced by the lens. When used as a headlight, my entire field-of-view (70°) is comfortably illuminated. The difference is particularly noticeable on low and/or during close-up tasks. I was pleased enough with the results that I decided to purchase an additional Atom.
On High I found the Atom AL acceptably bright for most tasks, a little more punch would have been fine too. The Low setting, on the other hand was limited to use during pitch blackness and/or for slowly moving about. Runtimes of 3-3.5 hours of flat regulated output on High using a primary (more using a rechargeable) and days of regulated output on Low was GREAT though.
The main problem wasn't light output, it was the excessively broad spill of the mule that frankly wasted a lot of light for my needs. I didn't need the upward lighting, nor the super wide left and right that was beyond my personal field-of-view, and worst was directed into the eyes of people who might be facing my general direction.Perhaps others had the same experience which was why FourSevens subsequently came out with the special reflectored model of Atoms, so I picked up an Atom AAF (an Atom AA with reflector), to try. To my disappointment, the special low profile reflector chosen for the Atom looked and projected just like my Quark Mini-AA. Still there's no point in living with a light that doesn't meet your needs, just move-it-out or mod-it-up, that's the CPF way!
I needed a beam half way between a hotspot reflector and the overly wide mule, perhaps an optic. But most optics are still too narrow or have funny beam patterns. I decided to try a plane convex (speherical) lens, like those found on inexpensive zoomies. As there was no off-the-shelf lens I could drop into the light, I got one sized as close as I could then sanded it down to fit into the Atom.
So, with the stock Atom AL as a control and the Atom AAF retrofitted with a convex lens, I made some comparisons of their relative brightness. The photos below show the results of putting a simple convex lens into the Atom.
Some background details to put the results in context.
-------------------------------------------------------------
The Atom AL (w/cr123a) (on left oem Mule)
- High = 110 Lumens
- Low = 6 lumens
The Atom AA (AA w/alkaline) (on right w/convex lens)
- High = 70 Lumens
- Low = 1.5 lumens
(Since I had the lights opened, I swapped the cool XP-G2's with a Hi-CRI Nichia 219b and 219c (4000K) as a bonus
)Atom AL mule on low @6 Lumens (left) vs Atom AA+lens on low @1.5 lumens (right) -
(due to the wide nature of mule beams, lights were only 6-inches from wall)
The photos don't show the full extent of the AL mule spill but the area is many times that of the lensed AA+ light. Yet, the illuminated areas of the lights have similar levels of intensity even though one light is supposedly outputting 4X the lumens (6 vs 1.5 lm) of the other.
When both lights are on High the illuminated portion of the 110-lumen AL mule (left) appears no brighter (actually less) than the 70-lumen AA+ (on right). The difference in person was greater than what may be evident in the photo.
Here is a profile of the beams showing the relative angles and thus the respective area being illuminated.
The AL in it's original form is spec'd as 120° (left), whereas the AA with lens (right) is now reduced to about 70°.
What's Going 'On?
--------------------
Basic geometry indicates that the area created by a 120° projection is 6X that of the area created by a 70° projection. Assuming this relationship transfers directly to the math involved with calculating area illumination, "harnessing" the light that was previously spread over the wider area should be 6X brighter when the same lumens are focused down to the reduced area created by the narrower lens beam (increased lux) . The photos (2 prior) of the AL (120°) vs the AF+ (70°) seem to bear this out, with the higher output AL (6 lm) appearing no brighter (actually less) than the lower output AF+ (1.5 lm) in the illuminated areas.
Results of adding a simple convex lens to The Atom AA mule
------------------------------------------------------------------------
GAINS -
- the illuminated portions on High now appear brighter
- the Low is brighter and more useable for my purposes, and
- the narrower angle means I no longer inadvetantly shine at people in my peripheral.
LOSSES -
- a smaller overall area being illuminated,
- the loss of a low moonlight mode,
- loss of some water tightness as my lens was hand-filed and not perfectly round (a small lathe would have useful).
- ability to stand either end, tail only now due to bump out from convex lens
On balance, I like the brighter narrower, but by no means narrow, light produced by the lens. When used as a headlight, my entire field-of-view (70°) is comfortably illuminated. The difference is particularly noticeable on low and/or during close-up tasks. I was pleased enough with the results that I decided to purchase an additional Atom.
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