NVG Tube differences

Our friends at FALCONCLAW know a lot of the Details of night vision devices. Today, they share their knowledge of image intensifier tubes (IIT) with us, namely the difference between the PHOTONIS 4G and the ECHO. Both are basically Gen 3 IIT, read our BASICS article for more information. But now to their insights: 

We wanted to do an honest review, and It’s so much easier to grasp the difference when you see performance of IIT’s with similar specs side-by-side. We all know that PHOTONIS 4G IIT's are more expensive than most of their counterparts. Even when comparing units with similar specs, you will find 4G's about 30% more expensive than for example ECHO's with similar metrics. So why is that, and is 4G really worth the hype?

PHOTONIS 4G

4G Technology is a set of capabilities described by minimum specifications of modern night vision to deliver to end-users the highest performance in all field conditions.

4G Night Vision standards are defined by:

• An Extended Bandwidth of photon collection to deliver a consistently high image quality in all environments (from below 400nm to above 1.000nm)
• A FOM above 1800
• A Resolution always superior to 57 lp/mm even in the most polluted light environments such as urban areas or when entering a building where the light is suddenly switched on
• A typical 0.75mm halo around the brightest objects seen in the image to provide the highest details around the light sources
• All PHOTONIS  4G tubes have expected lifespan greater than 7500 hours and work at extreme temperatures -32 to +49 °C for seven days.

PHOTONIS 4G vs ECHO

Both PHOTONIS ECHO and 4G IIT's come from the same production line. Therefore, compared to other commercial-grade IIT's, PHOTONIS ECHO is already a high-quality product. So, why some IIT’s are classified as 4Gs and some as ECHO’s?

First and foremost – IIT is classified as a 4G only if it exceeds mil-spec requirements. Whenever during the testing process the unit does not meet those requirements, it is labeled as ECHO. One may think that we only talk about the tube specifications that are shown on the datasheet. Yes, those attributes play some role in classifying the tube between 4G and ECHO, but the main difference is outside of shown specs.

During testing tube goes through series of environmental (e.g. survive -32 to +49C for seven days), electronics, durability (unit is expected to last more than 7000h) and other tests. Meaning – If you need to have high degree of certainty that your unit will work in any environments, conditions and will not fail you in the worst moments, you go to 4G. That's what mil-spec is for.

In addition to successfully completing more rigorous testing, 4G generally has:

• Less black spots and shadows
• 15% higher gain and sensitivity (not visible in specification) which are the main attributes for light amplification
• Longer lifespan (at least 7000h, ECHO does not have lifespan defined)
• Wider spectral range to deliver high quality image in all environments
• Smaller halo around the brightest objects
• Higher minimum requirements for most of the attributes

The actual test results

Although not all perks of the 4G can be seen on a performance review (like lifespan or environment test), we decided to take few of our devices out and set our night-ducks in a row… So let’s take a look at actual performance of the devices. To start, we took two devices from our stock with fairly similar specifications.

Following material was collected during a clear night sky far away from any big light-pollution sources like big cities. It was winter, so white snow reflected light from the stars. We used same cameras with exactly the same settings to capture the performance of the NVDs. 

As you can see from pictures, 4G is brighter due to higher gain and has more detail, although resolution on 4G tube is lower. When comparing the performance of a 4G and ECHO, even with similar attributes, you can expect 10-15% higher performance on the 4G, since not all the characteristics (like sensitivity) are displayed on a tube datasheet. And the performance difference is more evident as we wonder into woods.

As we wandered into darker woods, the environment became more challenging for the IIT’s. You can clearly see that due to higher luminance gain and sensitivity, the picture of 4G looks more sharp and clear.

When comparing tubes in light environment, then the difference is not so clear. 

You can notice little more stars on the 4G, but the image is quite similar. 
 

Let's sum up

Good thing is that ECHO/ECHO+ comes from the same line as 4G. So, the base-technology is already superior to any commercial-grade line. We have seen some exceptional ECHO IIT’s coming from PHOTONIS production lines, with absolutely amazing specifications! We know that ECHO’s don’t meet the 4G mil-grade requirements, but the tricky part is that we don’t know where in the testing process they ‘fell out’. Didn’t it pass some environmental tests or something wrong with image quality? This information is unknown. 

While ECHO is an amazing product for commercial users with very good price vs performance ratio, with 4G you can be 200% sure that the tube was tested in very demanding environments (even to the limit that IIT will not probably ever see during its lifetime again). PHOTONIS 4G is produced for users who need a reliable night vision device and do not compromise with quality or durability

PHOTONIS online

FALCONCLAW online