STEP 1 - Get your ATT (for restricted firearms only)
STEP 2 - Pack your night vision and helmet, etc.
In no particular order here are some tips for travelling with your night vision:
As the popularity of night vision continues to grow, demand for quality night vision has also grown substantially, leading to long lead times and pre-orders for night vision. Recognizing the need for some users to get their hands on night vision sooner rather than later, or for those on a budget, we have started to offer NNVT intensifiers in both green and white phosphor as the intensifiers are more readily available. North Night Vision Technology is based in China and they primarily manufacture intensifiers for domestic use. They have only recently begun international exports and we are pleased to be one of the stocking dealers.
TL;DR
What can you expect - qualitatively
The most common question we receive is how they are compared to Photonis Echos. Generally speaking NNVT intensifiers use older Photonis XD4/XR5 technology from about 10 years ago with some slight enhancements. It can be reasonably deduced that modern night vision (Echos) will outperform NNVT in almost all areas. This assumption holds true across the board as our detailed YouTube video below will show.
Before we compare, it should be noted that there are multiple variations of NNVT intensifiers in the marketplace currently.
As you start to climb beyond NVT5, the pricing gap between NNVT and Echos narrows significantly, negating the pricing advantage of NNVT. Historically the consistency of quality and after-sales support for Photonis has been superior over NNVT.
Gain
Based on a sample size of over 100 intensifiers, gain levels on NNVT intensifiers are - on average - about 25% lower compared to Photonis Echos as measured on the Hoffman test set, with all else being equal (same lenses).
Clarity/Resolution
Clarity on non-autogated NNVT intensifiers is significantly reduced compared to Photonis intensifiers in both high- and mixed-light scenarios due to lack of autogating. Those who own Photonis Echos and who might have "accidentally" turned their night vision on briefly during the day may have observed that there were no ill effects and the clarity remained quite high. This is because of the ultra-fast autogating technology proprietary to Photonis intensifiers. When non-autogated NNVT intensifiers are exposed to high light levels, resolution drops drastically to the point where it appears the device is out of focus. Attempting to achieve focus in high light scenarios is extremely difficult as the image will appear quite muddy regardless of focus, this will also be evident in night-time urban environments with bright light sources.
Here are two images captured with our Sony A7S3 rig with 16-35mm F/2.8 GMaster lens - the first is captured with NVT4 (non-AG), the second with Photonis Echo. You can immediately see the lack of clarity in the centre of the image (roof of house). Other images you may have seen online comparing NNVT and Echos were likely taken with a camera phone which automatically applies artificial sharpening to the image and deviates from what you would experience in real life.
Zooming in, the difference is more evident. You can clearly see individual shingles on the roof in the 2nd photo.
Both setups were independently focused using our Sony A7S3's focus peaking. Note that optimal focus was not achievable on the NNVT as the image output from the intensifier was too blurry due to lower MTF (Modular Transfer Function). This technical assessment agrees with most users' experience who we demo'd NNVT systems to - most mentioned that it was difficult to achieve good focus.
Low-light clarity for NVT4 and NVT5 is also reduced compared to Photonis Echos as the SNR is simply not as high and static or scintillation is present earlier on. As NVT4 intensifiers have a FOM range of 1200-1700, this generally translates to both lower resolution and/or lower Signal to Noise Ratio. This lower performance is to be expected from these lower specifications (specs don't lie!)
INTRODUCING NVT4-AG
Recognizing the performance gap in non-autogated NNVT intensifiers, we sought out an autogated version at a comparable pricepoint to bring additional value to these budget options. The NVT4-AG intensifiers we now stock offer similar high-light performance as Photonis Echos, at a lower price point, and start at 1600+ FOM, with some reaching almost 1700 FOM. The addition of autogating has two-fold benefits:
For a detailed analysis and breakdown of NNVT NVT5 (1700+ FOM), NVT4-AG (1600+ FOM), and Photonis Echo (1600-2000FOM), take a look at our video below:
Conclusion
Are NNVT's "comparable" to Photonis Echos? On the surface - non-autogated NVT4's render a useable image in non-challenging lighting situations. To the uninitiated, they may even seem good. But once you perform some basic side-by-side comparisons in challenging lighting conditions, you can easily see that Photonis Echos outperform non-gated NVT4's in all situations. Generally speaking non-gated NVT4s should be "good enough" for 35% moon or greater in the open, or areas with some moderate lighting.
With the introduction of NVT4-AG, the performance gap between Echos and NNVT intensifiers is narrowed and opens the usable operating envelope of NNVT substantially.
So who would benefit most from NNVTs? We always encourage those getting into night vision to consider their own unique operating environments and applications rather than relying on anecdotal, qualitative information or simply "going with what everybody else is getting". Generally we recommend NNVT intensifiers for hobbyists and individuals who are on a tight timeline or budget, or those who plan on using night vision in mild lighting conditions or those who will have supplementary illumination. Those looking to get into binoculars without breaking the $8,000 CAD mark should also consider NNVTs as it provides true stereoscopic vision while providing some budgetary leeway for ancillary equipment. NVT4-AG's provide tremendous performance-per-dollar value.
]]>As part of our Hand-Select process, we typically go through a consultative process to understand each end user's experience level, requirements, and application. That said, we ultimately provide a refined selection of intensifier specifications along with each intensifier's through tube photo, based on our understanding of each user's requirements.
This short article is to assist users in understanding the visual impact of each performance specification to aid in making an informed decision.
For convenience, we've highlighted the takeaways in each section in bold text for those of you who prefer to gloss over the details.
FOM (Figure of Merit)
Figure of Merit, most often referred to as FOM, is the result of multiplying an intensifier's rated centre resolution (RES) and signal-to-noise ratio (SNR). For example, if a Photonis Echo intensifier has a Res of 67 lp/mm (line pairs per millimetre - we'll get to this in the Resolution section below) and SNR of 25, then the FOM would be 1675. As Photonis Echos are between 1600-2000 FOM, and FOM can be a product of Res and SNR, sometimes you may have two intensifiers with the same FOM, but different resolutions. Example: two intensifiers both 1800 FOM, one is 66lp/mm and 27.27 SNR and another that is 73 lp/mm and 24.65 SNR. The intensifier with the higher resolution will visually "look" more clear but will have a noisier image than the intensifier with the lower resolution. FOM is simply a way to quickly determine a good intensifier from a great intensifier - example: Photonis Echo+ at 2000+ FOM will outperform Echos at 1600-2000 FOM. You will get either a higher Resolution or a higher SNR, and those are both good things. But FOM alone is not important when other specifications are present.
RES (Center Resolution)
Resolution is an intensifier's ability to show contrast and generally equates to what users experience as "clarity" or "sharpness". Generally speaking, the higher the resolution is, the more clear it will appear to you. Some may refer to this as "crispy".
Resolution is measured in Line Pairs per Millimetre. A Line Pair is a black line followed by a white line
A typical resolution chart will have increasing line pairs on a scale and this chart is observed through the device. The measurement is taken where the line pairs effective blur together and become no longer distinguishable.
Each intensifier will have a limiting resolution and most modern night vision will measure between 64lp/mm to 81lp/mm with Photonis Echos coming in around 66-73 lp/mm. Generally speaking most users will not be able to determine the difference between a 1-2 lp/mm difference but those with good eye sight should be able to discern a small difference between the extremes of 66-73lp/mm. One should also consider their own personal eyesight - often users prioritize resolution but their own eyesight is not 20/20 which essentially "wastes" the resolution boost.
It should also be noted that most night vision intensifiers' system resolution will drop as light levels increase (and is especially true for Gen3 systems; with Gen2+ systems like Photonis being much less affected due to superior autogating) and there is a "sweet spot" of lighting conditions where the resolution will appear best.
SNR (Signal to Noise Ratio)
Signal to Noise Ratio is often misunderstood as the holy grail of intensifier performance. Understanding the signal-to-noise ratio is easier when we better understand what signal and noise are separately. Signal is the true light being picked up by the photocathode within the tube; this is the image you see when the tube intensifies light. Noise is the "noise" or "static" in the image that you sometimes see when light levels are extremely low. This is analogous to images captured at high ISO levels on professional cameras, or static in a broadcast TV image when there is some interference. Noise can be considered a false positive. The higher the SNR, the less false positives or noise there will be in an image at low light levels.
Note that differences in SNR can generally be detectable in extremely low light levels (eg: dark room with a faint light source). Comparing two intensifiers in a room that is lit by a computer monitor, as an example, should not be a valid test of performance as the light levels in the realm of image intensification is quite high. This brings us to why SNR alone should not be as heavily weighed as it typically is. In a moderate lighting situation, SNR is not as much of a factor as there would be sufficient amount of light to generate a useable signal. Therefore, users should think about ambient lighting conditions in their primary operating environment. As an example - SNR is less important in moderately-lit urban environments. On the flip side, SNR is very important in deep heavily-forested areas.
Generally speaking, with all else being equal, most users typically cannot discern a 2 point difference in SNR in a practical environment. The difference becomes more apparent when the difference is 3 or more, and even then it would only be visible in an very low light environment.
EBI (Equivalent Background Illumination)
EBI (Equivalent Background Illumination) is essentially the amount of light through a device when there is no light on the photocathode. The higher the EBI, the more likely the device will put out its own light and provide you a false positive (the "background illumination"). In aggregate, this has the effect of giving you a "muddy" image in VERY low light conditions (near total darkness). EBI level determines the lowest light level at which an image can be detected, below that threshold, objects will be masked by EBI. EBI is also affected by temperature, the warmer it is, the higher the background illumination and vice versa. That's why your tube will likely appear more "clear" when it's cold.
A lower EBI is generally considered better.
That being said, in most head mounted, ground-based systems, the number of instances where there is absolutely zero light reaching the photocathode is extremely low and therefore EBI should not be weighted heavily in an intensifier selection decision. EBI is more of a factor for applications such as astrophotography where false positives are very undesirable as high EBI will appear as stars through the intensifier.
For an example of an EBI comparison, click on this link HERE.
In the image shown below, even with a "great" EBI figure of 0.2, because the ambient lighting conditions are so low, the image is quite grainy and supplementary illumination would typically be used, thereby negating the EBI advantage.
Halo
Halo is the ring of light that forms around concentrated light sources when using night vision. Halo is prevalent with streetlights, headlights, or other concentrated light sources. The lower the number, the less prevalent this effect will be, so for this specification, lower is ideal. High halo values may sometimes obstruct the target you are trying to see as it become a photonic barrier.
High Halo value on the left; low Halo value on the right
Photonis Echo spec sheets do not come with Halo values. Retailers who offer halo values for Echos are generally guessing.
Gain
Gain is how much the intensifier is able to amplify a light source. The higher the Gain number the more contrast your image will have and the more you will be able to visually render an image. Some would perceive this as brightness but high Gain with a low Max Output Brightness will still resolve a darker-looking intensifier. Also, a high gain but low SNR intensifier will yield a bright but noisy image. Because human eyes have a natural iris and dark-adapting ability that machines do not have, variances of 1000-1500 cd/m^2/lx should not be used as a determining factor in an intensifier selection.
Gain is typically measured in cd/m^2/lx on Photonis spec sheets and average between 9500 and 10500 on Photonis Echo white phosphor intensifiers and between 12000 to 16000 on green phosphor intensifiers.
Max Output Brightness
Max Output Brightness (MOB) is how bright the brightest signal will appear in the intensifier. This is equivalent to increasing the brightness on your phone, as an example, but not the same as increasing contrast (gain). Generally, MOB hovers around 5.6 to 6.2 on Photonis Echo intensifiers but again, because most human eyes have the ability to adapt to various lighting conditions, this should not be a determining factor in intensifier selection.
Conclusion
While we are committed to providing full transparency in the tube selection process, intensifier specifications can be very confusing. Most new users using night vision in a practical mixed-lighting setting will generally struggle to visually differentiate between the low and high ends of each intensifier bracket (eg: 1600 vs 2000 FOM; or 2000 vs 2300 FOM). The difference only becomes more transparent as you move more than 3 SNR points and/or 5-6 lp/mm in resolution (effectively when you jump from NNVT to Echo; or from Echo to Echo+), or if operating in challenging, extremely low-light environments. Differences in EBI and Gain are even more difficult to differentiate without tightly controlled lab-grade conditions or with specialty camera equipment. As always - think about your own unique operating environment and method of usage to help you determine what your requirements are.
From an absolute perspective, high SNR, high Gain, high SNR, and low EBI are always universally desirable, but as part of our Hand-Select process, we typically only provide the highest levels of performance for your given application for your review. Armed with the knowledge above, and this in mind, when you receive your top 3-5 intensifiers to choose from, the specification ranges are typically a 1-point SNR, and 2lp/mm difference in specs between choices, so therefore, we recommend new night vision users to pick between this subset based on screen quality and size/location of factory dark spots.
]]>We've captured all of the key features and differences and these can be viewed via our online spreadsheet HERE.
It can also be downloaded in PDF format HERE.
Fixed Bridge vs Articulating
This is most likely the most divisive and key decision you will make. Fixed bridge systems are typically stronger and more robust compared to their articulating counterparts due to the lack of a hinging mechanism. A particularly notable advantage of fixed-bridge binocular systems is that they are easier to work with generally speaking - to move the binocular out of view is typically done with a single motion via the NVG mount. Restoring night vision is also easily done and will always put the goggle in the exact same place every time. This simplicity has huge benefits in terms of repeatability and having less moving parts to actuate. Anybody who has tried to execute multiple tasks with and without night vision will appreciate the fewer steps required to use and stow fixed-bridge goggle systems - it's actually one of the advantage that ball-detent systems like the AVS6 and AVS9 systems have there operators would flip the goggle up and the ball-detent mechanism would immediately power the goggle down - simplicity is speed.
Conversely, articulating goggles have grown in popularity in recent years initially driven by the popularity of first the PVS-15, then PVS-31A and more recently the DTNVG/DTNVS. Since then a myriad of articulating system have sprung up. Articulating system have benefits such as the ability to roll individual pods out of the way (useful for admin tasks or if needing to have one eye use a thermal sight, as an example), and also stow the pods closer to the helmet to reduce perceived weight (due to reduced length of moment arm between the goggle's centre of gravity and the base of your neck. For those of you who remember Grade 10 Physics class - Torque = Force & Distance. Force in this case is gravity and if you reduce the distance between the base of your neck and the goggle, you otherwise would reduce the perceived "torque" felt by your neck and trap muscles). A lower profile goggle and helmet systems makes getting in and out of vehicles and low-hanging structures easier, so if those are use-cases specific to your application, articulating goggles may be worth exploring further.
Manual Gain vs Auto Gain
Most binocular systems on the market today do not feature manual gain primarily due to increased complexity (both from a manufacturing and a user perspective) and the fact that integrating a MX-11769 format variable-gain intensifier with pigtail has historically proven challenging or cost-prohibitive for housing manufacturers. However, with the introduction of 3-pin or 3-pad MX-10160 format intensifiers, the removal of the need to accommodate for a physical tail has made manual-gain goggles become more popular recently. Notable examples include the forthcoming Manticore-R and Samurai-R.
Manual gain can be beneficial in situations where the contrast between high and low light areas of an image need to be reduced (eg: urban areas). In these situations, the gain can be reduced so that objects behind a window (as an example) can be seen against a brightly-lit exterior. The ability to manually change the gain should be weighed against the practicality of adjusting throughout your use of the device - simply put, you may not want to dial your gain level perfectly for a specific scene, then enter a structure, and have to manually adjust your gain again. That being said, manual gain can be beneficial for lower-cadence, recce-type roles where the user can afford time to adjust gain to the desired levels.
A recently popular attachment that provides a pseudo-manual gain option to auto-gain devices are the adjustable iris aperture devices (such as our CHAD) that can be attached to any device's ocular lens. The principle is quite simple - by closing the aperture, you reduce the amount of light entering the intensifier and essentially create a very easy-to-use manual gain "knob". However, the downside is that you have to actuate each optical channel individually so the experience is not as seemless as a system-wide gain control.
Pod Auto-Off
A feature that's unique to most articulating binoculars is the ability for each optical pod to shut off power to the intensifier when the pod is rolled out of view. We believe this is a critical function for three reasons:
Note that not all binocular systems currently on the market have this feature (PVS-31A, BNVD-1431), but all of the systems we currently offer do.
Material Choice - Durability
This one is simple - do you value weight over durability? Typically metal-based housings such as the RNVG, RNVG-A, RPNVG, Manticore-R, Samurai-R, and Proton will be slightly heavier than their polymer-based counterparts (eg: Katana, LLUL-21, Aeternus, DTNVS), but offer a substantially higher level of durability. That being said - metal housings will typically impart more impact force onto the intensifier vs polymer housings which would absorb impacts and potentially break. But it is usually far cheaper to replace a broken housing, than replace intensifiers damaged by impacts.
System Weight
Another key consideration is system weight. Most binocular night vision systems that are assembled with milspec optics will come in between 500-550g with some outliers above 580g. Most users will find systems weighing more than 580g to feel cumbersome despite having a properly balanced helmet setup (via a helmet counterweight) as a heavier system will have a higher perceived "swing weight". This is a consideration due to the narrow field of view (FOV) of night vision and the need to constantly move your head. Some of these heavier binocular housing weights can be offset via lightweight optics but at both a higher financial cost and optical performance penalty. (See our article regarding lightweight lens systems HERE). This approach can be problematic as the cost-savings associated with heavier housings such as the BNVD-1431 or PVS-31C are essentially negated by the cost of the more expensive lightweight lens options, creating a paradoxical situation where you end up with an average system weight, but at a higher cost and lower optical performance.
As the prevailing performance of US Milspec lenses is still superior to lightweight options currently, shaving housing weight has become a popular (and preferred) avenue for users to reduce headborne fatigue. Housings such as the DTNVS, Katana, and LLUL-21 all feature significant weight reduction and come in around 460-510g. While the Katana and LLUL-21 achieve weight savings through design, and elimination of some features (IR illuminator, internal indicator lights, etc), the DTNVS offers a robust feature-set at a similar low weight. While durability has always been a concern for lightweight housing options, forthcoming and current metal-based housings like the Manticore-R, Samurai-R aim for a total system weight of 550g and should be considered as they become available.
On- vs Off-Board Power
While the concept of remote battery packs are not a new concept (AN/AVS-6/9's operated exclusively on offboard rear helmet-mounted battery packs), most consumer, ground-based binocular systems will have onboard power of some kind. Recognizing that most binocular night vision systems will require a helmet counterweight to balance the helmet, recently-released housings such as the LLUL-21, and Samurai-R have disrupted the market by moving power exclusively to the rear, and in the case of the Samurai-R even the the controls are rear-mounted. This relocation of the power to offboard has a tangible weight reduction with both of these systems weighing in at least 60-80g lighter than their on-board power counterparts. It should be noted that while some binocular systems that have onboard power with an optional offboard power option, this particular type of setup does not yield a significant functional weight savings as the weight of the battery receptacle is still present. Most offboard power options will power binocular NVGs for 24 to even 80 hours at a time without the need to change batteries so for those who will be out for extended periods of time, or those looking for a functional counterweight, off-board power may be worth exploring further. For most individuals onboard power is still the most popular option from a cost and complexity perspective.
On-Board IR Illuminator
Recognizing that most goggle-based IR illuminators are anemic at best in power output, some recent lightweight binocular options such as the Katana, Aeternus, and LLUL-21 have abandoned this feature altogether. Most NVG users will typically carry a much more powerful on-person or on-platform supplementary illumination making on-goggle illuminators redundant. That being said, the Boson Proton has two VCSEL-based illuminators can can output up to 500mW of IR illumination via its spot and illuminators (for reference, a full-power PEQ-15 illuminator outputs 30-50mW) that rival dedicated IR lights.
On-Board Indicator Lights
Another area of weight savings are onboard indicator lights for low-battery warning and IR illuminator indicators. As mentioned earlier, most NVGs will run for 16+ hours on on-board power and even more on off-board power, so with a bit of battery management, one can simply keep track of how much time is spent with a battery and swap as that timeframe approaches. Users can also insert a fresh battery prior to mission-critical moments to ensure that there's no power issues that may potentially occur. Alternatively, most goggles have easy-to-access battery compartments that can allow for quick battery changes without dismounting the goggle. Secondly - as the user can typically see whether or not the IR illuminator is on - there is no longer a reason to include an IR illuminator indicator light.
This Buyers' Guide will continue to grow and be updated as we add more options.
]]>Jerry-YM Pros:
MH25 V2 Pros:
Most night vision output screens measure roughly 18mm in diameter but through a night vision eyepiece, any imperfection is magnified several times to almost fill your complete vision. While nobody wants to see any spots in their field of view in their night vision, intensifier manufacturers have enacted specific standards when it comes to the maximum number of spots that can be allowed in any given zone.
The following image below shows the typical Hoffman zone chart with a number of reference spots along with their corresponding spot sizes.
It can be observed that there are two spots just on the cusp of about the same size as the 0.003" (yes that's 0.003 inches in size) reference spot in the centre of the image, with the remainder of the image being relatively clean.
Referencing the spot tolerance for Photonis Echos below, it can be concluded that the 2 spots roughly 0.003" in size actually fall within the spot tolerance of Zone 1. Any spots smaller than 0.003" are not classified as spots and are generally referred to as "peppering". Peppering exists on every intensifier tube and it's only a matter of whether your eyes are sharp enough to detect them which can be very difficult, given their size. While it has been rare to see an intensifier approach the maximum spot tolerance per the zone chart below, it is certainly possible and users should bear this in mind when selecting or otherwise passing on certain intensifiers.
Spot Size | Zone 1 | Zone 2 | Zone 3 |
0.009" - 0.012" | 0 | 1 | 2 |
0.006" - 0.009" | 1 | 2 | 4 |
0.003" - 0.006" | 2 | 4 | 6 |
But what does this translate to in real-world conditions? Taking this same tube outdoors, shown below is a typical scene.
So what is the takeaway? While large spots >0.009" and up can be very visually distracting, smaller spot sizes such as the ones shown at 0.003" typically blend into the image and become far less noticeable in a practical sense. When reviewing through-tube photos such as the ones showing the zone chart, it can be very easy to get fixated on screen quality, but how often are you staring at blank white walls? Intensifier manufacturers keep the general usability of their tubes in mind and that's why all tubes must fall within the specified spot thresholds.
As a last step, we also conduct a spot spec analysis using our Hoffman test rig which measures the spot size via image analysis, removing subjectivity.
]]>We're proud to announce that we have substantially upgraded the way we capture and show through-tube photos beyond current industry norms.
Taking photos with a handy camera phone is what most night vision retailers do today and what we also used to do. While expeditious, this method has had limitations and caveats including:
Continuing to push the boundaries of providing objective information and transparency in the night vision purchasing process, we are now combining some of the best image capture techniques with the technical sophistication of our Hoffman night vision test set. Using a high-end Sony A7S3 mirrorless camera with 16-35mm F/2.8 G-Master lens and a custom PVS-14 lens adapter, we are able to capture through-tube photos with precise repeatability, completely eliminating any variables via the use of fixed white balance, aperture, shutter speed, ISO, colour and picture profile, and focus. Each tube is loaded into our test rig and manually focused and calibrated before the image is captured. While this takes significantly more time and effort, the resulting images provide the highest levels of objectivity and detail. By leveraging the Hoffman zone chart, we are also able to show and verify the presence of factory dark spots in relation to zones 1 through 3. Better matched pairs of intensifiers for binocular NVGs are also now possible as the hue of each intensifier can now be relied upon as a selection criteria.
What does this mean for you, the consumer? This means that you are now able to examine and compare each of our tube photos without worrying whether the focus on the camera phone has drifted; or if the colour difference between tubes is due to the white balance settings on the camera drifting, and many other unknowns.
We believe night vision is a substantial investment for most, and by providing this additional level of due diligence, we hope that our customers can make the most informed purchasing decisions and have full peace of mind that what they are looking at on their screen is what they will receive. No surprises.
]]>So functionally, what does 2000+ FOM potentially get you? As one of our blog posts pointed out, FOM is simply the product of Centre Resolution x Signal-to-Noise Ratio. This means that by guaranteeing a higher baseline FOM rating, you would be able to access either higher Resolution, or higher SNR, or potentially both. While standard Echo intensifiers hold their own and yield a very clean and rich image in many lighting environments (and in some cases, surpass US Gen3 performance), the higher performance numbers provided by Echo+ can be beneficial in demanding lighting or distance situations where some extra performance is required.
Where does Echo+ stack up against Photonis' premium offerings - 4G and 4G+? On paper, Echo+ will provide the same performance as a 4G tube as long as the specs are equal. Echo+ simply has less stringent screen cosmetic requirements so the presence of factory dark spots may be higher than 4G. That being said, they fall well within acceptable operational requirements and is as follows:
Spot Size | Zone 1 | Zone 2 | Zone 3 |
0.009" - 0.012" | 0 | 1 | 2 |
0.006" - 0.009" | 1 | 2 | 4 |
0.003" - 0.006" | 2 | 4 | 6 |
Taking this a step further, 4G+ is simply an even higher guaranteed level of performance that starts at 2300 FOM. Again, if the specs are equal, Echo+ intensifiers that may be available (although rare) at 2300+ FOM will yield similar levels of performance as 4G+, but at a much more palatable pricepoint.
Just as we selected Photonis Echo as our primary intensifier line due to its phenomenal performance-to-price ratio, we feel that Echo+ takes this one step further and provides our users with an even higher tier of performance while still maintaining the same high level of value.
]]>This is a follow-up discussion to the YouTube video published in Q2 2022
This is the updated video featuring RPO 3.0
In the following series of images, we demonstrate some of these trade-offs in a side-by-side comparison between US Milspec optics and RPO 2.0 and the latest 3.0 using tightly-controlled testing conditions to remove bias, and user subjectivity.
The test setup:
In the first test we have the standard black and white checkerboard contrast and light-level test:
There is substantial light fall-off at the edges of the image. This is because the RPO 3.0 lens features a reduced exit diameter. Not only does this physically limit the amount of light that would reach your eye, but optimal viewing distance has also been decreased. A technical discussion with RPO engineers confirmed that the eye relief is set at 25mm or 1 inch which is a very short distance away from your eye. This means that using any sort of eye protection including low profile goggles (eg: Oakley M-frames) will result in perceived vignetting or occlusion of the edges of the image. The situation is further exacerbated as the profile of the eye/face protection increases (gas masks, etc). The decreased eye relief is confirmed via the in-person experience, as pushing the device further away from the operator's face results in loss of image in the periphery. Photos circulating online showing no visible vignetting with RPO 3.0 lenses are likely taken with the camera pressed up to the eyepiece - an unrealistic use-case.
You can see the difference in viewing window size below:
The reduction in signal is further confirmed when we analyze the footage using Adobe Premiere's vector scope in raw Luma:
Notably not only does the periphery of the image have lower signal, but the peak is also lower comparing between Carson Industries and RPO 3.0.
The same footage, now analyzed using the RGB Parade:
Besides some blue fringing at the peak, the Carson still scores higher than RPO 3.0 across the board.
Other measured tests conducted using the Hoffman ANV-126A-001 test rig have stated that the RPO lenses (both 2.0 and 3.0) feature "higher light transmission". The reason that may be the case is that our particular PVS-14 lens adapter setup places the point of optical convergence away from the "ideal" 25mm eye relief that the RPO 3.0 was designed for. This is due to the shorter overall length of the RPO 3.0 eyepiece preventing our lens adapter from being mounted closer to the optimal 25mm distance. However, it should be pointed out that the distance between the PVS-14 lens and camera lens is fixed for all tests, and the Carson industries yields a consistently superior image, shown below in real-world testing. In practice, this means that to get a comparable image to US Milspec, a system with RPO lenses must be forced closer to the operator's eyes.
As gain is scored on the Hoffman ANV-126A as a singular, overall value, one other reason for the claim of higher light transmission may be due to the higher flare giving higher light levels but lower overall useable information (think Michael Bay / JJ Abrams lens flares). This can be seen below:
In the images above, a few key notes can be taken away:
In an effort to try to recover some of the lost periphery, the RPO 2.0 eyepiece is swapped back in. It should be noted that the RPO 2.0 eyepiece lens cell does not have the reduced exit diameter as the RPO 3.0 and the resulting image confirms that the peripheral edges of the image is retained and vignetting is removed compared to Carson US Milspec.
There is however, a downside to the RPO 2.0 eyepiece and that is rainbow artifacts at the periphery (1 o'clock)
It is also noticeable that RPO 3.0 and the "2.5" combo exhibits odd crown-shaped light flaring artifacts seen below:
These oddly-shaped artifacts are not present on US Milspec lens systems:
Conclusions:
While weight reduction and increasing operator comfort can be important, this currently comes at the cost of decreased detection capability, distracting image quality, reduced operator eyebox, and increased cost. While the results above are conducted in real world lighting scenarios, it should be noted that they were conducted in an urban environment. Rural or forested areas will show reduced difference in user perception.
The lack of factual side-by-side comparisons and limited pool of available information and ability to try these lens systems in person has led to the perceived notion that "more expensive" simply equals "better" when the data and images shown above show otherwise. As our original review stated, whether or not reduced weight is worth the trade-offs, should be a highly user- and application-driven decision.
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In the last 5 years, the NV world seems to be caught up with "FOM-Fever" and while FOM does offer some useable information to aid in a purchasing decision, it was actually only developed by government agencies as a way to determine import/exportability of tubes.
The actual definition of Figure of Merit (FOM) is the product of Signal-to-Noise Ratio (commonly expressed as SNR) multiplied by Centre Resolution (in line-pairs per millimeter)⠀⠀⠀⠀⠀⠀
FOM = SNR x Resolution⠀⠀
The reason why FOM doesn't matter, especially when SNR and Res is available is because you can have a tube that has a very high SNR, and low Res, up against a tube that has a low SNR and high Res, and both could have the same FOM. ⠀⠀⠀⠀⠀⠀⠀
Example: Tube 1 has 67lp/mm and 32 SNR; 32 * 76 = 2432 FOM⠀⠀⠀⠀⠀⠀⠀⠀
Tube 2 has 76lp/mm and 23 SNR; 76 * 23 = 2432 FOM⠀⠀⠀⠀⠀⠀⠀⠀
Despite the identical FOM numbers, the first tube will provide a very balanced image, while the 2nd tube will provide a very detailed, but noisy image.
Each data point on the spec sheet provides information on how the tube performance in various lighting scenarios. As an example - SNR becomes important in threshold lighting situations, centre resolution provides information on clarity. EBI will tell you how the unit performs in ultra-low-light situations (eg: astrophotography mostly). That is why we try to stay away from using FOM and ALL of our systems ship with their own individual tube spec sheets showing Gain, EBI , Resolution, SNR, etc. We also email you the tube photo of the actual tube you will receive, in advance of shipment.⠀⠀⠀⠀⠀⠀⠀⠀⠀
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With Photonis Echos, the Resolutions are mostly around the 66-69lp/mm range (although there are outliers from 62 all the way to 74), so if two tubes have roughly the same EBI and Gain, in our opinion, it would be very difficult to tell the difference between a 1800FOM tube and a 1950FOM tube. The difference becomes more apparent when the FOM differential is more than 200 (eg: 1600 vs 1950)⠀⠀⠀⠀⠀⠀⠀⠀⠀
As always, email us with any questions.
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What is collimation?
You may have heard of this term somewhere in your search for night vision and possibly dismissed it as yet another night vision jargon but in fact, collimation has one of the most important roles to play in binocular night vision.
Believe it or not, binocular night vision housings come with optical pods that often do not line up perfectly. Collimation is the process of aligning the two independent optical axes of each pod so they both point exactly straight in three dimensional space. Why is this important? When using a pair of goggles that are not properly collimated, the human eye and brain tries to correct the misalignment by either crossing your eyes subconsciously, or your brain has to work harder to mentally align the two images. Over time this can become tiresome and can result in fast fatigue compared to a properly calibrated set of goggles.
Pictured are some through-tube photos of a binocular device on our Hoffman collimation bridge. How the collimation bridge works is that the goggle sits on a very precise location on the Hoffman test set and two distinct reticles are presented to each optical pod (you can actually see what each reticle looks like in the first photo). Then the bridge is installed over top of the goggle in a precise location and prisms essentially merge the images together into one eyepiece. This is very difficult to achieve without a proper test set or a custom-built precision collimation rig.
This device in the first photo was not assembled or calibrated by us and it looks like it was collimated using one of the DIY methods. The first photo is how it was received, notice that you are essentially seeing double. Your brain will naturally try to correct for this and cross your eyes. The problem is that while the misalignment is obvious looking at a two-dimensional photo on a screen, this is not obvious when looking through the goggle as your brain may naturally try to correct for this, and essentially make you cross-eyed.
The second photo is after it has been properly collimated. The white cross hair sits perfectly in the middle of the black square and the resolution test chart numbers lined up - this is perfect collimation AND perfect diopter calibration.
If there is an individual or company selling night vision but does not own a collimation rig, there is a high likelihood that collimation was not performed at all. This results in that is barely serviceable but far from perfect. Some may even try to convince you that proper calibration and collimation is not necessary. We demand perfection and so should our customers and the wider night vision community. Unfortunately without these tools or an in-house quality control process, there is no way to verify perfect collimation, calibrated diopter, amongst other things. All night vision is not built equally. Don't live with "good enough". Screen the retailers you are thinking of buying from and ask them about their build process and tools. Demand more.
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A new line of PVS-14 lenses made by Rochester Precision Optics (RPO) have been gaining popularity in recent months due to their reduced weight over standard PVS-14 lens assemblies. We acquired a set for Testing and Evaluation and to determine viability as a future offering. Here are our findings:
Setup
The test above was conducted as follows:
Camera: Sony A7S3 with 16-35 Sony G-Master F/2.8 lens mounted on Peak Designs aluminum tripod; PVS-14 DSLR direct lens adapter
Settings: 1/50s shutter; F/2.8, manual white balance, 24fps, S-Log3 colour profile, manually focused
Night Vision Device: CH/PVS-14 Pro with objective retaining ring removed to facilitate swapping of objective and ocular lenses
Image tube: Photonis Echo MX-11769 white phosphor intensifier (same tube/device used for both shots)
A 10s clip was recorded first with Carson, then the PVS-14 dismounted and the front and rear lens assemblies replaced with RPO, and re-recorded. The videos were imported into Adobe Premiere for cropping, zooming, and re-sizing only.
Observations:
There does not appear to be any perceived performance difference between the two in terms of light transmission or low-light performance. The footage does not appear to differ in terms of increased brightness nor reduced noise. As the scene was specifically chosen to be a threshold lighting situation where noise was present, if the RPOs or Carsons exhibited less noise, it would mean that more light was entering the image intensifier but this did not seem to be the case. The larger exit aperture on the RPO does not seem to provide any tangible improvement benefit.
There is however, some pincushion distortion present on the RPO, as can be seen on the edge-crop (3rd sequence, observe the vertical bookshelf support). This distortion appears to be mild but is visible and noticeable when panning the device left and right when viewing vertical lines. This may be of concern for users who are using this in urban environments where these are more prevalent.
Conclusion (so-far):
This was only one set of lens against one scene. Additional testing is required but early indications show that the practical optical performance gain is negligible or non-existent. It could be conceivable that RPOs have a higher performance benefit in specific lighting scenarios with specific light sources (eg: sodium-based, or LED-based street lamps, as an example). The weight differential between RPO and Carson is substantial and warrants additional investigation and consideration for applications where weight is a concern with a trade-off being slight pincushion distortion.
Full-resolution screen captures:
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This was originally posted on our Instagram HERE.
We get asked a lot about the benefits of the Cadex mount and how it compares to the G24. As always, we'll show you.
The biggest difference between the Cadex mount and the G24 is the increased fore/aft travel. Not only does the Cadex get the incumbent device closer to your eyes, eliminating the "drinking straw" effect and giving you full view of your viewing window, it also extends substantially farther than the G24, providing additional versatility for other mission-essential equipment for gas masks and other high-profile face protection.
The second difference is the adjustable dovetail built into the Cadex shoe. This clever mechanism allows you to dial in the perfect solid lock-up that is so coveted by NVG users and even accommodates for off-spec dovetails. Two black-oxide screws ensure this adjustment does not come loose.
The third difference is the height adjustment. The Cadex has an increased height adjustment range allowing users the flexibility to use a wide variety of devices. A common downside to the RNVG housing is the short distance between the optic centre-line and the dovetail mount, resulting in the RNVG sitting too high and forcing users to unnaturally tilt their helmets down to accommodate. The Cadex mount takes the height adjustment a step further by providing two additional mounting holes to completely re-mount the base, providing an additional one inch of height differential.
The fourth difference, although subtle, is the increased tilt adjustment range. This flexibility will allow users to dial in the perfect tilt angle of the incumbent device, removing any need to angle the helmet to accommodate.
The last differences lie in the use of materials on various controls. On the Wilcox L4 family of products, the adjustment mechanisms are cast with polymer and the height adjustment lever is a frequent source of breakage. On the Cadex mount, these control surfaces are all made of aluminum for increased strength and durability.
The Cadex is made in Canada 🇨🇦 and offered with a full warranty.
All images can be clicked to show the 4K high-res screen caps.
First up is the classic Carson "teal" lens.
Last is current-production Carson.
Lastly, here are some screen caps showing off-axis flare suppression. Pay attention to the light source inside the garage at 8 o'clock.
Observations (in no particular order):
• Old Carsons maintain sharpness over a larger centre zone (pay attention to the markings on the satellite dish on top of the garage), but off-axis flare suppression is not as good as Edmund or Carson when panning
• Edmund lenses improve on flare suppression over old Carson but has less very slightly less contrast than current Carson lenses
• Off-axis flare suppression is slightly better on Carsons vs Edmund
• All three lenses exhibit excellent rectilinear performance
Conclusions:
Carsons appear to represent the best balance in terms of contrast and flare suppression compared to other lenses in this control group. Old Carsons are no longer produced, and a larger "sweet spot" is desirable, but flare suppression falls short of current-production lenses. How much does all of this really matter? In a practical sense, higher contrast will yield better detection levels. That being said, the difference is subtle and slight but present.
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2) Does not consistently power up Photonis tubes. This is the only housing I have worked with where some of the housings (and it's important to note that there was no consistency to this) would simply not be able to power Photonis tubes up. Some housings would power up one tube only, and some housings would power up both tubes, and yet some housings didn't work at all. It was maddening. All of the same tubes powered up perfectly in a non-BNVD-1431 housing. Argus assured me that this was due to the higher amperage requirements of Photonis MX-10160 format tubes and why US Gen3 tubes like L3 and ITT work. Some builders have resorted to using 3-pin MX-10160 tubes. Not only does this technically not make much sense (why put a variable-gain tube inside a fixed-gain housing?) They suggested that we use lithium batteries. This did nothing to solve the issue as we used all sorts of batteries including brand-new lithiums, rechargeable NiCD, NiMH, Alkaline, etc. One would think that the housing would be designed for the #1 ITAR-free tube manufacturer in the world, rather than ITAR-restricted grey-market tubes...Further investigation yielded that if you re-soldered parts of the PCB on SOME housings and used less solder, this issue went away. Sometimes. So this might just be a huge QC issue, more than anything.
3) Spongy, unreliable power button. Some of the power buttons would require an unnaturally firm press and there was no tactile click to register the press. As the only user-available function on the goggle, and as a secondary "programming" button that requires users to press the button "4 to 5 times quickly" to enable/disable certain features, the button left a lot of things to be desired.
4) A number of hardware issues including but not limited to: undersized hinge o-rings, cracked hinge washers, off-spec screws that stripped easily. Some housings came with missing screws also. We remedied this by installing upgraded hardware with our builds. As the only retailer at the time with a digital purge rig, we were the ones who brought the water sealing issues to the forefront and was one of the primary reasons for us dropping the housing from the product line. The housing leaks from a number of areas such as the hinge o-ring, the one-way pin at the hinge joint, the power button, various gaskets, etc. These were all confirmed via iterative testing by us and a host of other parties.
The steps to remediate the leaks include, but are not limited to:
While they could all be rectified, we do not believe these to be assembler-level modifications that are easily achieved, especially for a housing that, at the time, retailed for $1350 CAD. Not to mention this only addresses one out of the other serious concerns on the housing. The waterproofness of a housing is not the sole determining factor regarding its reliability.
As we mentioned at the beginning of this article, weeks of testing and countless faulty housings went through our hands. Initially we brought these issues to light in private to the Canadian distributor and Argus and urged them to discontinue immediately while these issues were addressed. However, they were more than happy to continue to sell the housings despite the issues, opting instead to offer band-aid solutions and workarounds. The combination of the lack of manufacturer and distributor-level ethics and support led to our decision to drop the 1431, and publish this article.
To be fair, we were willing to overlook issues #3 and #4 as they were either easily remedied or a gripe. It was really the combination of all of the issues and Argus' unwillingness to remedy these issues that led to our ultimate decision to move on from the 1431. We had tried reaching out to Argus to address these issues but they seem to be more focused on publishing the next "Gen3" or Mk2 release of the goggle featuring an improved power knob with variable gain, a physical switch for Photonis tubes (although we're not sure why this even necessary, as it is absent on every other goggle in the market), IR illuminator and skeletonized pods. All of those features sound really great, but if the reliability is not present, then the housing is useless in our eyes.
We completely understand that most consumers are looking for a night vision goggle that powers up two tubes, uses PVS-14 optics, for a good price, but the reliability issues and astronomical failure rates makes the BNVD-1431 a non-viable product out of the box. Even if the cost of the housing retailed for less than half of what it currently is, we still would not carry it due to the major issues above. We too were fooled with the promise of a good binocular NV housing with our evaluation units and we want to apologize to everybody for hyping up the BNVD-1431, and profiting from it. That being said, we will continue to honour our 12-month warranty for these systems to the best of our ability.
We know there's a huge demand for a mid-level goggle and we're in the middle of testing some other binocular goggle housing options that will be rugged, reliable, and well-priced.
Nowadays, we're inundated with options including:
* denotes ITAR-restricted housings
If you remove the ITAR-restricted housings, you'll notice that you actually aren't left with too many options. So with your hard-earned money, which one should you buy?
As a night vision retailer and builder, here are what we would consider the top 5 things to consider when thinking about your ultimate binocular NV housing:
1. RELIABILITY
This one may seem more obvious than most, but reliability is often overlooked and assumed. Most people think that a binocular housing simply houses tubes with 4 wires going from the battery to each tube, but there are a myriad of other electronics present to handle various functions, including, but not limited to:
All of these need to work in harmony to guarantee a high-functioning, reliable goggle system.
2. DURABILITY
Again - another item that can be overlooked. Has the housing you purchased been tested in a professional capacity? Can it withstand a 1.5m drop onto concrete? Will it shut-off when bumped?
3. WATERPROOFNESS
While there is very little overlap in the Venn diagram of what SEALS do and the large majority of us do, that doesn't mean we should not want a housing that's waterproof. The last thing you want is to get caught out in the rain, moisture enters your unit and either significantly reduces your tube lifespan or kills your tubes altogether. Has the housing you're considering been tested for submersion? For how deep and for how long?
4. CONTROLS
Do the controls make intuitive sense? Are they a derivative of legacy PVS-14 controls that are as ubiquitous as AR-15 controls? If not, do they at least have a tactile feedback when actuated?
5. QUALITY CONTROL
Does the manufacturer of the housing you are considering have a stringent quality control program in place? Can all of the housings be considered reliable? Has there been reports of issues from other users? Is the manufacturer responsive to feedback?
As 2021 marches on, and other binocular systems continue to be published (eg: Boson MNVG), it's important to be cognizant of these considerations even before you consider the feature set. We'll cover that in a subsequent blog post.
In the meantime, we're currently testing a few other housing options, keeping on top of the considerations mentioned above. Stay tuned.
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Here we are comparing the highest end L3 unfilmed white phosphor technology to some of the highest performing Echo grade Photonis tubes we had.
What we see here is one data point to show the context of how Photonis Echo compares to the best tubes available in terms of lower gain. What does lower gain really equate to for practical use? The target silhouette in the photos is at a distance of around 45-50 feet in a mixed lighting interior environment common for operations inside a structure. Both the target and the night vision device are in the darkest interior rooms, while the area in between has more ambient light. By making small alterations to the overall ambient conditions in the room of the target, we can see progressively how Photonis compares to L3 unfilmed in a scenario ranging from dark to extreme darkness.
Without a doubt, the unfilmed Gen 3 tube provides more gain and image intensification at all ambient light levels. However, when you add contextual elements, the lines between them performance wise are a bit more blurred.
Target identification is roughly equivalent between the options despite the difference in gain level in all ambient conditions. And by "roughly equivalent" we mean that the use of IR illumination would likely be necessary at the same ambient level for either solution.
Now, a photo is not the same as real, live use in real time. Would the L3 unfilmed provide a slightly quicker reaction time in the MIDDLE ambient condition (near total darkness)? Yes, we believe it would. Whether or not it is a quantifiable advantage is less clear.
This is just one use scenario. Other scenarios may yield different results.
All images are courtesy of @nocturnalitygear
]]>Let's call a spade a spade right off the bat and be honest - Echos are higher-performing and more affordable than any other comparable image intensifier tube available, but yes, they have factory dark spots in the form of small dots in the image. Second - while Echos initially were 4G run-offs, this is no longer the case and Photonis is now making these to fill the product line. Third - factory dark spots and blemishes are two different things. Factory dark spots are as a result of any number of things, typically a piece of dust trapped in between the MCP and photocathode plate, as an example, or some other by-product of the manufacturing process. Blemishes are user-induced tube damage like laser burns, leaving a weapon-mounted monocular behind a red dot on high, etc.
Rather than try to describe the dark spot tolerances, we thought we would show you via the standard NSN 5855-01-548-9489 spot chart.
This chart conveniently divides the viewable area of any tube into three zones: 1, 2, and 3. Zone 1 is probably your most critical zone and likely where your eyes will naturally focus. You will likely find yourself centering your head to whatever you're aiming so that your target falls within this zone. Notice however that Zone 1 is actually quite small in comparison to Zone 2. Zone 2 will be where you'll likely pick up surrounding information to form "the bigger picture". Lastly, Zone 3 is a very narrow band on the outer edges. Typically this zone, while somewhat useful, suffers from slight edge distortion and light fall-off (vignetting) from optics. This is what we would consider the periphery and the limits of detectable information, and probably the least critical of the three zones.
Next, moving onto the spot sizes, the chart conveniently provides reference blemishes located above the Zone 1 ring, starting with 0.003" and going up by 0.003" increments up to 0.015".
Using a representative sample size of 50 Echo tubes, we're including a through-tube photo of what we would call the "worst" out of the batch. You can click on the image for a full-resolution version (opens a new window).
Working our way through the zones, there is one Zone 1 spot that's roughly 0.003" and two smaller ones that - because they are smaller than 0.003" are not considered spots; two Zone 2 spot, one at 0.003" and another at 0.006" in size; and finally three 0.003" spots in Zone 3.
On the opposite end of the spectrum, within that same batch, here is a tube photo of the "best" tube.
There is a single Zone 3 spot that is 0.003" or less in size.
Bear in mind that the above represents a random sample of 50 tubes. Formally, Echo tubes have the following spot tolerances. Any tube with more spots than these specs are automatically rejected and destroyed by Photonis. Note that the existence of any spots above 0.012" in size are automatically rejected also.
Spot Size | Zone 1 | Zone 2 | Zone 3 |
0.009" - 0.012" | 0 | 1 | 2 |
0.006" - 0.009" | 1 | 2 | 4 |
0.003" - 0.006" | 2 | 4 | 6 |
There may be instances where there are more spots of smaller size than is allowable per zone. For example: three 0.003" spots in Zone 1 are allowable.
Finally, fixed-pattern noise such as honeycombs (typically most obvious during high light situations) and slight shading are not considered blemishes.
All of our systems are built with these tubes described above and will be drawn at random for builds. We will work with you to determine eye dominance and place the tube with the cleanest image over your dominant eye.
We capture each and every tube image at the time of build completion and store it in our database with its respective serial number and spec sheet.
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