Vastlite Spectra Bow Zoom LEP Prototype Review
Vastlite Spectra Bow LEP Prototype#
- Specifications
- Introduction
- Torch in use
- Build quality
- LED, bezel, lens, reflector and beam
- Size and comparison
- User interface
- Batteries and charging
- Performance
- Beamshots
- Thermal Images
- Conclusion
- Price
- Product page
Specifications#
| Brand/model | Vastlite Spectra Bow |
|---|---|
| LEP | Transmissive-type |
| Maximum lumens | 730 lm |
| Maximum beam intensity | 649,000 cd |
| Maximum throw | 1,610 m |
| Battery | 1*21700 |
| Onboard charging | Yes (USB-C) |
| Material | Aluminium |
| Modes | 2 |
| Blinkies | Strobe, SOS, Beacon |
| Waterproof | IP68 |
| Review date | September 2026 |
Introduction#
The Vastlite Spectra Bow is a 21700-sized LEP torch with a head that can be twisted to zoom and change the colour between white, red, green and blue.
Bruce from flashlightgo provided this prototype for early feedback before going into mass production.
Vastlite is now launching the Spectra Bow. It was given the name “Spectra” for the RGB (Red, Green, Blue) filters and “Bow” to keep in line with the current range of LEP torches from Vastlite.
The results in this review should be taken with a grain of salt. I have reviewed a prototype. It is not the final version.
They have updated the RGB filter mechanism, changed the driver, and changed the LEP module to an SMD LEP in the final version.
I have reviewed a fair few torches from Vastlite:
- Vastlite Versa Bow
- Vastlite Bow
- Vastlite Sima
- Vastlite General
- Vastlite Minima Bow
- Vastlite i7
- Vastlite Bow SFT25R
flashlightgo kindly provided this torch for review. I have not been paid for this review nor have I held back my opinions of this torch.
Packaging#
The prototype came in a simple cardboard box with bubble wrap to protect the torch.
The final version is likely have much nicer retail packaging similar to the other Vastlite torches.
Torch in use#
The torch feels comfortable to hold.
It is controlled by a side switch and by twisting the head.
The zoom mechanism allows this torch to be used as as floodlight or a spotlight. It can be used every day rather than just for looking at things far away.
The tailcap has four long holes that could be used for a lanyard.
The torch can tailstand.
Build quality#
This Vastlite Spectra Bow prototype is made of aluminium and it has a matte black anodised finish.
There is plenty of knurling on the head and the tail for extra grip.
There are no sharp edges.
The threads came well lubricated and the tailcap turns smoothly.
There is a notch on the driver for the positive end of the battery and a spring at the tail for the negative end.
Overall, the build quality is good. It may be better on the final version where they have improved the RGB filter mechanism (it sometimes locks up on the prototype).
LED, bezel, lens, reflector and beam#
The Vastlite Spectra Bow prototype has a transmissive-type LEP module. The final version has an SMD LEP.
There is a glass lens in front of a biconvex lens.
Zoom In vs Zoom Out
When the head is twisted to change the colour, the filter mechanism is rotated.
Red
Green
Blue (it doesn’t look violet, this is just the colour temperature being a bit off with my camera)
CCT, CRI, and duv#
I have taken Correlated Colour Temperature (CCT) and Colour Rendering Index (CRI, RA of R1-R8) measurements with the torch positioned ten metres away from an Opple Light Master Pro III (G3). I measured the centre of the beam.
The CCT is around 5500K, the CRI is around 51 and the Delta u, v is positive (green).
The beam produced has an extremely intense hot spot with minimal spill when the lens is zoomed in.
The beam has a floody dim beam and a bright ring around the edge when the lens is zoomed out. This is because there is one big lens in front of the LEP module.
| Zoom | Mode | CCT (K) | CRI (Ra) | x | y | Duv |
|---|---|---|---|---|---|---|
| In | Low | 5565 | 50.8 | 0.3307 | 0.3870 | 0.0225 |
| In | High | 5559 | 51.8 | 0.3308 | 0.3933 | 0.0251 |
Calculate Duv from CIE 1931 xy coordinates
Dimensions and size comparison#
Dimensions#
I took the following measurements using a digital caliper.
| Measurement | Unit (mm) |
|---|---|
| Length | 149.25 |
| Head diameter | 50.06 |
| Tube diameter | 25.92 |
| Tail diameter | 29.02 |
Weight#
I took the following measurements using a digital scale.
| Weight | Unit (g) |
|---|---|
| Torch | 186 |
Size comparison with its competition#
From left to right: Vastlite Spectra Bow, Vastlite Bow, NLIGHTD LZ1
From left to right: Vastlite Spectra Bow, Vastlite Bow, NLIGHTD LZ1
User interface#
The Vastlite Spectra Bow is controlled by an electronic side switch and two rings on the head that rotate to control the zoom and colour.
The first ring can be twisted to zoom in and out.
The second ring can be twisted to change the colour (white, red, white, green, white, blue).
There are two main modes: Low and High. And three blinky modes: Strobe, SOS and Beacon.
| State | Action | Result |
|---|---|---|
| Off | Press and hold | Low |
| Off | Click | On (mode memory) |
| On | Press and hold | Cycle (Low, High) |
| On | Click | Off |
| Any | Two clicks | High |
| Any | Three clicks | Strobe |
| Strobe | Three clicks | Cycle (Strobe, SOS, Beacon) |
The final version has a few extra features:
| State | Action | Result |
|---|---|---|
| Off | Four clicks | Lock |
| Locked | Four clicks | Unlock |
| Any | Five clicks | Toggle switch backlight on or off |
Mode memory#
This prototype has mode memory. Low and High are memorised.
Strobe#
Strobe has a constant frequency.
Strobe, SOS, Beacon
I measured Strobe, SOS and Beacon with a Zoyi ZT-706S oscilloscope using High Speed mode.
Low voltage protection#
There is low voltage protection. There is a warning flash around 3.12V and the light turns off around 2.78V.
I tested low voltage protection by connecting the driver of the torch to a bench power supply and then by lowering the voltage from 4.2V to 0V.
Pulse Width Modulation#
I did not notice any visible PWM (flickering).
I can hear PWM on the Low mode.
Low, High
I measured the PWM of the light with a Zoyi ZT-706S oscilloscope.
What I like about the UI#
- Shortcut to Low from off.
- Shortcut to High from off.
- Shortcut to Strobe from off.
What could be improved#
It is ok as it is.
Batteries and charging#
Battery#
This prototype did not come with a battery. I used a Molicel P45B 21700 to test it.
Most button top and flat top 21700 3.7V Li-ion cells work.
I tried the following cells:
| Cell | Top | Compatible? |
|---|---|---|
| Molicel P42A 21700 4200mAh | Flat | Yes |
| Molicel P45B 21700 3.7V Li-ion 4500mAh | Button | Yes |
| NEXTORCH 21700 3.7V Li-ion 5000mAh USB-C | Button | Maybe |
| XTAR 21700 3.7V Li-ion 5000mAh | Button | Yes |
The NEXTORCH cell was a bit long. It worked but I could not fully tighten the tailcap.
Charging#
The Vastlite Spectra Bow has built-in USB-C charging.
Power supply: XTAR TYPE-C45IC
USB Meter: ChargerLAB Power-Z KM003C Amazon Australia
Room temperature: 15 C
It took 3 hours to charge a Molicel P45B 21700 4500mAh cell from 3.03V to 4.20V at a rate of 5V/2.4A inside the torch.
The indicator light is red while charging and it becomes green when charging is complete.
Power supply compatibility#
I tried the following power supplies with the built-in USB-C charger:
| Power supply | USB Type | Protocol | Does it charge? |
|---|---|---|---|
| Google Pixel Power Adapter | USB-C | PD | Yes |
| PinePower Desktop | USB-C | PD | Yes |
| PinePower Desktop | USB-A | QC | Yes |
| PinePower Desktop | USB-A | Yes |
USB-C to USB-C charging works.
Performance#
A user manual was not provided with this prototype.
Vastlite sent a digital copy of user user manual for the final version with a different driver. Here are those details:
| Modes | Low | High |
|---|---|---|
| White (Spotlight) | 85 lm | 615 lm |
| White (Floodlight) | 100 lm | 730 lm |
| White Distance (metres) | 600 m | 1,610 m |
| Green (Spotlight) | 38 lm | 275 lm |
| Green (Floodlight) | 45 lm | 325 lm |
| Green Distance (metres) | 310 m | 780 m |
| Blue (Spotlight) | 1.5 lm | 15 lm |
| Blue (Floodlight) | 2 lm | 17 lm |
| Blue Distance (metres) | 175 m | 485 m |
| Red (Spotlight) | 6 lm | 42 lm |
| Red (Floodlight) | 7 lm | 45 lm |
| Red Distance (metres) | 135 m | 355 m |
| Runtime | 6h | 5min + 3h |
| Beam Intensity (cd) | 649,000 |
I tested the light using a Molicel P45B 21700 4500mAh cell.
Lumen measurements#
I used a bench power supply to measure the current at turn on:
- Low 0.75 A
- High 4.62 A
| Colour | Zoom | Mode | Lumens @turn on | Lumens @30 sec | Lumens @10 min |
|---|---|---|---|---|---|
| Red | Out | Low | 11 | 11 | 9 |
| Red | Out | High | 39 | 24 | 10 |
| Blue | Out | Low | 1.7 | 1.7 | 1.7 |
| Blue | Out | High | 18 | 17 | 5 |
| Green | Out | Low | 20 | 20 | 20 |
| Green | Out | High | 127 | 103 | 39 |
| White | Out | Low | 78 | 77 | 73 |
| White | Out | High | 527 | 482 | 163 |
| White | In | High | 552 | 500 | 167 |
Runtime graphs#
I used my own DIY lumen tube with a TSL2591 sensor and forked bmengineer’s project RuTiTe to record runtimes.
Note: Lumen measurements may be off by 10% with my DIY lumen tube.
The room temperature was approximately 15 C.
Runtime#
Here is a summary of the runtime results:
| Colour | Zoom | Mode | Runtime | Turn off | Final voltage |
|---|---|---|---|---|---|
| White | Out | High | 2h 16min 59s | 2h 37min 33s | 2.91 |
| White | Out | Low | 4h 30min 54s | 4h 50min 16s | 3.03 |
“Runtime” is the time until the output reduces to 10% of the output at 30 seconds (as per the ANSI/PLATO FL1 2019 Standard).
“Turn off” is the time until my DIY lumen tube no longer detects more than one lumen.
“+” indicates that the light remained on after recording had stopped.
The output is well regulated.
Throw#
I took lux measurements with a UNI-T UT383BT at 30 seconds with the lens zoomed in. Low and High were measured at ten metres.
| Mode | Candela measured (cd) | Distance (m) |
|---|---|---|
| Low | 126,800 | 712 |
| High | 751,100 | 1,733 |
Beamshots#
I went to a local park and I aimed the torch at a tree 70 metres away while using High.
Beamshots were taken using a Sony RX100M2 using 3.2", f3.2, ISO 100, 5000K WB.
Vastlite Spectra Bow (High) Zoom Out#
Vastlite Spectra Bow (High) Zoom Out Green Filter#
Vastlite Spectra Bow (High) Zoom Out Blue Filter#
Vastlite Spectra Bow (High) Zoom Out Red Filter#
I then went to another park and I aimed the torch at a tree 100 metres away while using High.
Beamshots were taken using a Sony RX100M2 using 1.3", f3.2, ISO 800, 5000K WB.
Vastlite Spectra Bow (High) Zoom Out#
Vastlite Spectra Bow (High) Zoom Middle#
Vastlite Spectra Bow (High) Zoom In#
Vastlite Spectra Bow (High) Zoom In Green Filter#
Vastlite Spectra Bow (High) Zoom In Blue Filter#
Vastlite Spectra Bow (High) Zoom In Red Filter#
Vastlite Versa Bow (High) Zoom Out#
Vastlite Versa Bow (High) Zoom Middle#
Vastlite Versa Bow (High) Zoom In#
NLIGHTD LZ1 (Turbo) Zoomed Out#
NLIGHTD LZ1 (Turbo) Zoomed In#
Vastlite Bow (High)#
NLIGHTD L4 Green (High)#
NLIGHTD L4 Prototype (High)#
NLIGHTD L3 (High)#
NLIGHTD L2 (High)#
Thermal Images#
I used a HIKMICRO B20S thermal camera to take thermal images of the torch while using High.
Room temperature: 15 C
| Time (mm:ss) | Max Temperature |
|---|---|
| 00:00 | 16.3 C |
| 01:00 | 23.4 C |
| 02:00 | 30.1 C |
| 03:00 | 33.9 C |
| 04:00 | 35.5 C |
| 05:00 | 37.0 C |
| 06:00 | 38.7 C |
| 07:00 | 40.4 C |
| 08:00 | 42.0 C |
| 09:00 | 42.3 C |
| 10:00 | 41.4 C |
Conclusion#
The Vastlite Spectra Bow is an improvement over the Vastlite Versa Bow.
It has larger lens, a longer beam distance, more lumens, and an RGB filter mechanism built-in (no more swapping filter covers).
The zoom feature makes these types of LEP torches much more practical. It can be used as a floodlight close up or as spotlight far away.
It’s not all sunshine and rainbows. There is a dull spot in the middle of the beam when zoomed out and using the torch as a floodlight. A few companies have solved this problem by either having two biconvex lenses in front of the LEP module or by having a digital diffuser (Liquid Crystal Diffractive Electro-optic Lens as Acebeam calls it) behind a biconvex lens like the Acebeam W35. These solutions cost a bit more.
If you are looking for an RGB torch, then the Vastlite Spectra Bow is worth considering. It can help reduce the amount of torches that you are carrying.
Pros:#
- Good build quality.
- Good beam distance.
- Output is well regulated.
- Zoom and colour change mechanism is easy to use.
- Built-in USB-C charging.
Cons:#
- The zoomed out beam has a ring with tint shift around the edge and a dull centre.
Price#
The Vastlite Spectra Bow is US$209.99 at flashlightgo.com (affiliate link)
The Speras TH4 is US$149 but it has an LED instead of an SMD LEP and the performance is not the same.
Product page#
Get 25% off with the code “Spectra Bow” (valid 1st to 7th of October 2026 only).
Vastlite Spectra Bow at flashlightgo.com (affiliate link)
I may earn a commission if you use an affiliate link or a promo code. This will help fund future torch reviews and tutorials.