NNVT - Comparison & Various Grades

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

• NNVT intensifiers are available in multiple grades (eg: NVT4, NVT5, NVT4-AG, NVT5-AG, NVT6, etc)
• NNVTs will generally under-perform against Echos across the board (NVT5 and below) but are a good budget option to get in the game
• Non-autogated NNVTs will have a sharp drop in clarity in mixed-lighting scenarios

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.

• NVT4 - non-autogated
• NVT4-AG - AUTOGATED
• NVT5 - non-autogated
• NVT5-AG - AUTOGATED
• etc.

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:

• protection of photocathode in high light scenarios
• increase in resolution in high or mixed-light environments

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.