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What You Need to Know


    1.  Introduction to Using Outdoor Illumination

     2.  4 Things You Need to Know about Reflected Light From Outdoor Objects

     3.  Illumination Comparisons of Common Objects 

     4.  Light Optimized for Mesopic Vision Reveals Far More Detail Than Red LEDs

     5.  Multiple Light Sources Reveal More Surface Detail and What Is Hidden In Crevasses Or Shadows

     6.  Continually Lighting the Area Around and In Front of the Feet Improves Footing, Confidence, and Hazard Avoidance

     7. Using UVA Light


1. Introduction to Using Outdoor Illumination


As avid hiker-trekkers, we have often been out on tough terrain late at night in all weather conditions before or after capturing a sunrise/sunset, or before/after a wildlife photo-op.

What is needed to improve personal outdoor lighting and to reveal more of what we enjoyed seeing during the day?

What's Wrong With Today's LED Headlamps and Flashlights? 

LEDs provide long bulb life, but you have probably already observed that everything exhibits less color range or detail at night using even the  "brightest" LED headlamps and flashlights, regardless of the LED power. Browns and reds are the most obvious weaknesses, but other important detail is also lost along with much contour and depth perception.

At night, many outdoor hazards can be difficult to quickly identify such a brown roots in brown dirt or mud, ground clutter, slick or slimy areas, holes, drop-offs, uneven surfaces and even vegetation detail using even the "brightest" LED lights.  Unfortunately, it can be difficult to tell what you are missing since you cannot see it because of over saturation in the middle spectral range.

How can we get closer to realizing the experience of crisp morning daylight when we on or off the trail at night

What Makes Our Morning Day-Vision Crisp, Clear, and Colorful?



After learning understanding what was being illuminated had been largely ignored, we conducted our study of the spectral characteristics of potential hazards and natural materials over a 5-year timeframe. Because the objects encountered in different environments is large, we tested surfaces almost every type terrain on earth.  


Taking Spectral Measurements: In addition at testing samples in our lab, we made instrumentation portable for on-location measurements. Thousands of surface reflection measurements were taken using flat-spectrum sunlight-like LED lights we had created (Similar visible spectra to sunlight, but consistent wherever we were). When practical, we also measured reflected light spectra from objects or terrain surfaces using natural lighting, and when wet or dry. 


Furthermore, we also took large numbers of on-location reference spectral measurements of the sun, open sky, lighting under multiple types of tree-cover, by water, and reflected light from large-area landscape scenes in varied terrain.

There have been many studies of retail products and packages illuminated by different lighting because of specific economic interests. For example, bread, and meat on display require high red content LEDs so fresh products appear fresh. Clothing is brighter with UVA in the spectrum.  This list goes on for other products and packaging.


Many retailers had to remove original Poor-CRI LEDs and reinstall warmer LEDs with more spectral red light (e.g., clothing stores, bakeries, meat & fish markets, and others).

However, tree roots, bark, leaves, logs, slimy or rough surfaces, briars, and animal burrows have been largely ignored since they are seldom sold in retail locations.


We initially wanted to improve the illumination of hazards and natural objects along trails for our own use and to better understand some "glaring" inconsistencies regarding portable lighting outdoors.

 Example Direct Sunlight Spectrum               Example Skylight Spectrum    

The spectra of direct sunlight and skylight vary with location, date, time, proximate reflective surfaces, and atmospheric conditions, but these curves are generally representative of clear sky spectra.


As you may know, direct sunlight is line of site from the sun, while skylight comes from almost all overhead directions. The spectrum of daylight on what you are observing is also effected by any reflected light from objects in the proximity, or filtered light from trees or clouds.


Notice the Direct Sunlight spectrum has cyan and red peaks! This often occurs on clear days.  Cyradiance spectra also 'uniquely' have cyan and red peaks (even more enhanced). This is the opposite of what you get with other LED headlamps and flashlights that boost yellow just to put higher brightness-lumen values on a specification, instead of giving you quality light that really improves vision for the widest range of objects.


Getting Close to Sunlight and Mixed Daylight to OWLSIGHT and LEGLIGHTS Spectra

The OWLSIGHT Mode 4 with the ActiveV filter (white-blue appearing filter) over the 3 LED triad reasonably resembles direct sunlight, while the OWLSIGHT with the ActiveV filter over the large LED (also LEGLIGHTS in Mode 4) resemble a mix of direct sunlight and skylight, similar to daylight.  The reds and Cyans are boosted in both Nulumina Precision Illuminators for better overall visual acuity.


We characterized over 200 other headlamps and flashlights, some at point of sale, some being used by other people in the field, plus many we purchased for use in our lab (since some tests were destructive). We used spectrometers, usually with our integrating spheres, a goniometer, and set-ups for water, dust, temperature, light patterns, and battery life testing.  All had poor spectra, many had poor beam uniformity. Some of the most respected and expensive brands were up-to 5X off their own luminance and battery life specifications and few met the water resistant rating. 


See the "About Us" section of this website for more information on Nulumina's optical, electrical, materials, and environmental testing capabilities.




Every kind of light spectra is useful for something, including typical super-bright white LED headlamps and flashlights.

Typical spectrum LEDs are great for signaling (unless there is a lot of dust or haze), reading black & white text (if low power), and when looking at distant objects that are light in color or reflective with high contrast (especially whites, yellows, & pale greens).  Poor light is better than no light. Keep your old flashlight for special purposes or the light you use when your surroundings are almost all pale colors such as dry grass,  near-white sand, concrete, painted surfaces, or most other non-fluorescent man-made surfaces.


Generally useful light is more sunlight like. It best matches the way our brains and eyes work. 


High "brightness" can make us feel like we see more even through or perception of detail is degraded for many objects because our brains are used to associating higher brightness (up to a point) with security. In the natural worl d higher brightness usually means more light. With LEDs from the unnatural world, this tricks the eye for many objects.



Still, even when at home you should grab a Nulumina Cyradiance illuminator if you are sorting navy and black socks, or grilling fish or meat.

Typical "Other" LED Spectral Weaknesses :


1) Indigo to Violets & UVA,       2) Cyans,        3) Red to Deep-Reds


In addition to colors, a full spectrum of light wavelengths also effects our ability to better perceive translucent films like dew or oils, and fine texture or structures on surfaces because different wavelengths of light scatter, diffract, or refract at different angles. 

2.   4 Things You "Need To Know"

About Reflected Light From Outdoor Objects

Today's LED Headlamps and Flashlights Are Poorly Matched To The Reflected Spectral Characteristics Of Most Natural Outdoor Surfaces! 


Remember, almost all colors you see result from the colors in the lamp that illuminates these surfaces. These surfaces determine which parts of the illuminating light spectrum reflect back to you. This means is that the colors and detail you see are dependent on that illuminating light spectra as much as the nature of the objects themselves.


In our study of thousands of typical outdoor surfaces, we found these  observations to be important for vision at night.

2a) "Substantial" amounts of RED spectral light (610-700nm) reflects from almost-all natural surfaces. Brown, gray, and even most black or green appearing natural objects reflect considerable red light. Red light effects color and pattern detail, even if you do not specifically see "red" in an object.

A wide spectral range of visible red wavelength light reflects from most objects. Sunlight and even overcast daylight provides a full visible light spectrum, including a large relative amount of all red wavelengths. 

2b). Considerable CYAN light reflects from most dirt, mud, leaves and stems, bark, and much more. Cyan light effects the color variations of many natural objects.


Your eye's rods are most sensitive to cyan spectral light (480-510nm). Cyan provides the longest distance dark-adapted vision for a given amount of light. Your eye's rods are 100X more light sensitive than your eye's cones, but your rods are only used for vision when you are dark-adapted.  Cyan and red together are important to reveal details about plants and soil, and even which green plants have been recently stepped upon, soils overturned, or blood when you are tracking.

2c) Blue, Indigo, Violet (400-480nm)  and UVA (380-400nm) light are intense components of scattered light from blue sky (why sky appears blue). These wavelengths are also present in light from cloudy skies. This light typically comes at surfaces around you from all overhead directions during the day, often including shallow angles. These short wavelengths are part of our visible our color range. UVA and and violets induce fluorescence in many natural and created surfaces which we see as brighter colors. These wavelengths also play a role in the perception of thin films and clear or highly reflective surfaces such as wet objects, ice and snow, glass, oils or waxes, and more.

4d).  Yellow and Green (530-600nm) light is reflected from many objects, and often most intensely from many white or pale/pastel appearing objects. These wavelengths are in the middle of the photopic (Cones only vision) spectrum so these photons appear much "brighter" compared to violets, blues, cyans, oranges, or reds. 


Other headlamps and flashlights output mostly output yellow light along with with a narrow blue intensity peak due to the blue LED chips used under their yellow phosphors.

3.  Illumination Comparisons of Common Objects 

4. Light Optimised for Mesopic Vision Reveals Far More Details Than Red LEDs


Cyradiance Technology Can Provide Extreme Long-Distance Illuminated Viewing because of the unique Cyan spectral Boost

(Not just dark-adapted searching for other lights in the distance)


If the spectrum, amount of light, and beam angles are adjusted correctly, you can obtain super "Mesopic Vision" where your eyes Cones and Rods work together.

Mesopic Vision allows you to see color differences, patterns, and even read maps with red markings much better than with red LEDs.  

See your perimeter and see far into distance while using minimal battery power. Nulumina's ActiveRed filters can make almost any white light into a mesopic vision compatible light. By super-efficiently converting other light wavelengths into red light instead of just blocking and wasting light power, a huge amount of the entire-visible-red-spectra light is output with just enough of the rest of the light spectrum to not lose other detail you need. Red LEDs only emit red and then, effectively emit only 1/4 the visible red light spectrum so little detail remains even for most red reflecting objects. Why not see more and stay dark adapted?


The OWLSIGHT and LEGLIGHTS have useful illumination spectra created for great Mesopic Vision, depending on your objectives and level of dark-adaption. Proper procedural use can provide great mesopic night vision with minimal risk of flashing yourself and needing to restart your dark-adaptation. 

Nulumina's  OWLSIGHT has our unique ActiveRed filter Technology to enable your true mesopic vision in Modes 3 or 4.

And, can also support mesopic vision in full-spectrum Mode 2 without a red color tint

 LEGLIGHTS also support mesopic vision in Mode 2  using deep-red enhanced Cyradiance Technology light. This provides for mesopic vision that is optimized for roots, soils & use on the legs. Only minimal red tint is observed in the LEGLIGHT Mode 2.

If you use the ActiveRed filter over the OWLSIGHT 's large LED and use Mode 4, you can see almost all detail well (red tinted) while highlighting certain materials such as blood better than even "bloodlights" (Best with LEGLIGHTS in Mode 1 or 2).

Try simulating early morning daylight  using the OWLSIGHT headlamp in Mode 4 with no filter, and the LEGLIGHTS in Mode 4. Tilt the lamps and your head so the beams with overlap on the objects of interest from ground level to chest height in your close proximity. Your vision range is huge with the illuminators in this mode even if you are not dark-adapted, but objects in the beam-overlap zone should simulate many effects of after sunrise sunlight at your back.

This effective "Studio-Lighting-Zone"zone is typically 4-30+ ft in front of you and 0-10ft above the ground, depending on your head and leg positions, angle of the terrain, and your dark-adaptation. The zone can be raised vertically with LEGLIGHTS on the wrists or top of the arms.

5. Multiple Light Sources Reveal More Surface Detail and What Is Hidden in Crevices or Shadows


Become An Mobile Lighting Studio for Better Vision?

Using an Owlsight headlight and 2 LEGLIGHTS together can help you better approximate several effects the of morning sunlight at your back, or a photographic lighting studio.


On a clear after-sunrise morning with direct sunlight at 10-45 degree angles to most terrestrial objects, scattered skylight also illuminates objects from many other angles (including shallow angles). This is a highly revealing lighting arrangement when the sun is behind the observer.


When attempting to simulate the morning daylight effect, we noticed that we were also recreating a " wearable and mobile photographic or video studio like design".  


After some experimentation, we found that wide-angle, broad-spectrum blue/violet-enhanced floodlights (LEGLIGHTS Mode 4) worn just above the knees plus the (OWLSIGHT headlamp, Mode 3, No-filter) revealed far more visual detail of surfaces than any single light, AND made the foot-forward zone obstacles and contours more visible.


A broad light spectrum and multiple light angles work together for much of the effect of morning daylight vision. It is typically not be practical to create all the angles of skylight and other reflected light, but this 3 point system is better than single light source systems.

And, It takes less than a minute to strap-on or take-off an OWLSIGHT head lamp and 2 LEGLIGHTS thanks to the quick-release bucle design

 6. Continually Lighting the Area Around and In Front of the Feet Improves Footing,                                  Confidence, and Hazard Avoidance


You probably don't even realize it, but the pupils of your eyes frequently glance down at your feet. If this view is obscured, especially on unfamiliar or uneven terrain, you feel less foot-sure and are more likely to stumble. 

Continually illuminating your feet AND the zone at-least 3 meters (Over 9 ft) in front of your feet improves your confidence and footing (If running, double this illuminated distance).


The wide peripheral illumination and shallow angles of LEGLIGHTS are ideal for revealing ground contours otherwise only easily visible in daylight.

Because LEGLIGHTS are closer to the surfaces being illuminated than a headlamp, they can properly illuminate a large area of ground using minimal battery power.

7. Using UVA light

Both the OWLSIGHT Headlamp and LEGLIGHTS can provide UVA light with an intensity peak mostly in the 390-400nm range. 

OWLSIGHT Headlamp with no filter over the 3 small LEDs*:

        "Mode 1" provides almost-only UVA light 

        "Mode 2" provides a full-color spectrum with a relatively intense UVA spike (Much more relative UVA than skylight)

        "Mode 4" provides a smaller relative UVA peak in a full-color spectrum (similar relative UVA to rest of spectrum as skylight in proximity)

        * Negligible UVA light is present in any mode from the OWLSIGHT if either active filter is over the small LEDs


        "Mode 1" provides about 75% relative radiant flux UVA light, with the balance being mostly violet-to-blue light and trace cyan+green light.

        "Mode 4" provides a full-color spectrum with a relatively intense UVA spike (More relative UVA to the rest of the spectrum than skylight)


Ultraviolet light in the wavelength range of 380-400nm is present in all daylight (both sunlight and skylight) even on cloudy days, in moonlight, and UVA is commonly used in many consumer ultraviolet flashlights. UVA is considered in the non-visible range by most authorities, but it is actually visible to most people as a purple color light. The UV wavelengths that cause tanning and other harmful skin effects are much shorter wavelength light, so forget turning your tent into a tanning salon on a trail even if you used 10, 000 of our headlamps. Do avoid staring into our UVA light or any other intense light. Nulumina's special small UVA LEDs are much more powerful than other similar size and shape UVA LEDs, but they still output less UVA power per square foot of illuminated area at a 6-9 foot distance than typical sunlight.

UVA can induce strong visible range fluorescence in a great many objects such as scorpions, some plants and fungi, clothing washed in typical detergents with whiteners, urine stains, bed bug tracks, and fluorescent gear.


Using UVA outdoors, you see the visible range light emitted from the fluorescent objects, and not so much the relected UVA light itself from the surrounding objects. Therefore fluorescent objects strongly stand out against non-fluorescent backgrounds in the dark.

In some modes on the OWLSIGHT and LEGLIGHTS, broad-color spectrum light is emitted that contains a much larger relative amount of UVA light than skylight (e.g., Mode 2 on the OWLSIGHT without a filter and Mode 4 on LEGLIGHTS). Nulumina is the first to introduce this type spectrum that uniquely allows you to see surrounding detail while still highlighting fluorescent objects at the same time as was shown in the scorpion photo sequence in this website. This effect is best when you are at least partly-dark adapted (after ~10-15 minutes in low-light).


Hint: We have found a useful mode in scorpion country to be Power Mode 2, or Mode 4 on the OWLSIGHT with the ActiveRed filter over the large LED. Use Mode 1 on the LEGLIGHTS unless the terrain is especially rugged, Then use mode 4 on the LEGLIGHTS).

Don't have scorpions where you live?    You might be surprised!    Better check your shoes!  (We took this photo set in Costa Rica)

Scorpions live in most of the USA and Canada (and the rest of the world). They are noctournal and hide well in the day, BUT they all glow in UVA.

For a list by species and by state, check out, Canada:      Any in Mexico? You've got to be kidding!

The "Enhanced UVA" modes on the OWLSIGHT and LEGLIGHTS uniquely let you see UVA fluorscence, while still seeing most everything else.

There are many fluorescent objects in nature, including certain plants, lichen, algae, bacteria, fungi, insects, amino acids, urine stains, etc...

Fluorescent outdoor gear glows, as does most clothing (even without special dyes) if ever washed in "typical" detergents containing brighteners. 





Yes, You Can Better Avoid Many Hazards!

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