Jerry-FB20 vs. Jerry-FB: What’s Changed? Part 2 – Night Vision, Thermal Fusion & Real-World Performance

In Part 1, we went through the physical changes between the Jerry-FB20 and the original Jerry-FB, covering everything from the housing and controls to the optics and thermal focus.

But specs and hardware changes only tell part of the story.

What really matters is what happens when you actually look through them.

Does the FB20 produce a better night vision image? Has the thermal fusion improved? Is the difference noticeable when you move around with the goggles, rather than simply comparing two static images?

For Part 2, we put the Jerry-FB and Jerry-FB20 side by side under the same conditions to find out.

What We’ll Cover

1. Night Vision Image Quality

2. Thermal & Fusion Performance

• Thermal Hardware & Display
• Startup Speed & UI
• Fusion Image Quality & Latency
• Outline Mode
• Red Hot Mode
• Built-In IR Illuminator

3. What the FB20 Improves in Actual Use

 

1. Night Vision Image Quality: Same Tubes, Different Results

To make the comparison as fair as possible, both units were fitted with entry-level NNVT FOM 1400+ non-autogated white-phosphor image intensifier tubes. That matters because IIT quality can have a huge influence on what you see through any night vision devices. With equivalent tubes installed, however, the difference becomes easier to see.

The FB20 shows less chromatic aberration and better-controlled distortion toward the edges of the image. The difference isn't night-and-day, but if you've spent enough time behind night vision, it's the kind of improvement you start noticing fairly quickly.

In terms of the overall viewing difference, it reminds us somewhat of moving from the Jerry-31 to the Jerry-31S/ELF-31H: the fundamental night vision experience is familiar, but the image feels better controlled around the edges.

 

A Note About the Tubes

The NNVT tubes used in this test are entry-level models, typically with an SNR in the 22–25 range. That means some noise is expected once ambient light levels get very low.

For general recreational observation, though, they're perfectly usable.

If you're building a higher-performance setup, the FB20 can also be configured with higher-spec tubes such as NNVT NVT5AG FOM 1600+, NVT7 FOM 1800+, and NVT7+ FOM 2300+.

There is another interesting option for enthusiasts who already know exactly what tubes they want: the FB20 is also available as a housing kit and supports a wider variety of IIT configurations, including MX-10160, three-wire, and MX-11769 pigtail formats.

That flexibility may actually matter more to experienced NV users than a bundled tube specification. If you already own a pair of tubes you like—or you're putting together a specific build—you have more room to configure the system around them.

One Functional Difference Worth Knowing

Before getting into image quality, there is one functional difference worth pointing out.

The original Jerry-FB can operate in three basic configurations: Night vision only, thermal only, or thermal fusion.

Based on the FB20 unit we tested, the newer model offers night vision and thermal fusion, but does not provide a standalone thermal-only viewing mode.

For users who primarily buy an FB-series device for fused night vision, this may not be a major issue. But if you regularly use the original FB as a standalone thermal viewer, it's something worth knowing before upgrading.

2. Thermal & Fusion Performance

Both the Jerry-FB and Jerry-FB20 use a 640 × 512, 12 μm thermal detector, so the headline detector resolution itself hasn't changed.

The FB20, however, pairs that detector with a 1280 × 1024 OLED display running at 60 Hz, using a capsule-shaped display area together with updated image-processing algorithms.

And this is where looking at specifications alone starts to become misleading.

On paper, you might see “640 × 512” on both devices and assume the thermal experience is basically the same.

Through the eyepieces, it isn't.

2.1 Faster Thermal Startup

One of the first differences you'll notice doesn't involve image quality at all.

The FB20's thermal channel starts up faster than the FB's.

We're only talking about a difference of a few seconds, so it isn't something that transforms the device on its own. But it is one of those small quality-of-life improvements that becomes more noticeable over repeated use.

Power up the goggles, activate thermal, and the FB20 simply gets you there sooner.

For anyone interested in seeing the difference directly, watch the FB vs. FB20 startup comparison on Instagram：https://www.instagram.com/p/DcQgNL4ONvF/

2.2 A Cleaner, Easier-to-Read UI

The user interface has also been redesigned.

Compared with the original FB, the FB20's UI looks cleaner and is easier to read through the eyepiece.

This might sound like a minor detail when you're reading a spec sheet, but UI design matters quite a bit on a device like this. 

You're not looking at a smartphone screen in a brightly lit room. You're reading status information and changing settings through an eyepiece, often in darkness. 

The less visual clutter you have to deal with, the better.

 

2.3 Cleaner, Smoother Fusion

This is probably the most important part of the comparison.

Side by side, the FB20 produces a cleaner fusion image with noticeably better visible detail.

But image sharpness isn't the only improvement we noticed.

During testing, the FB20 also showed lower perceived latency in fusion mode. As you move your head or track something in the scene, the thermal overlay appears to follow the underlying night vision image more closely.

That makes the viewing experience feel smoother and more natural.

And this is an important distinction when talking about fusion systems.

A good-looking static fusion image is one thing. A fusion overlay that still feels comfortable when you're actually moving is another.

For users who spend most of their time in fusion mode, this may be one of the more meaningful upgrades from the original FB.

2.4 More Defined Outlines

The difference is also easy to see in Outline Mode.

Rather than filling the thermal target with a solid thermal overlay, Outline Mode emphasizes the contours of warmer objects. This can be useful when you want thermal detection without covering as much of the underlying night vision image.

In our side-by-side comparison, the FB20 draws finer and better-defined contours around both people and buildings.

Take a look at the comparison images below, particularly around the human figure and the edges of the buildings.

The FB20's outlines appear more controlled, making it easier to distinguish the thermal information from the underlying scene.

For users who prefer Outline Mode over a heavier thermal overlay, this is a particularly useful improvement.

  

2.5 The New Red Hot Mode

The FB20 also adds another thermal palette that wasn't available on the original FB: Red Hot.

In this mode, warmer targets are highlighted in red, making people and other heat sources immediately stand out against the night vision image.

Will everyone use Red Hot as their default fusion mode?

Probably not.

Thermal palettes are very much a matter of preference and environment. But having another option is useful, particularly in scenes where you want warm targets to visually pop as quickly as possible.

 

2.6 A Weaker Built-In IR Illuminator

So far, most of the differences favor the FB20.

But not all of them do.

The built-in IR illuminator on the FB20 is noticeably weaker than the one on the original FB.

If you regularly rely on the built-in illuminator as an active IR light source, the original FB has the advantage here.

If you normally use passive night vision or pair your goggles with an external IR illuminator when additional illumination is needed, this limitation may matter considerably less.

 

3. What the FB20 Improves in Actual Use

After spending time with both systems side by side, the FB20 feels like more than an exterior redesign.

The biggest difference isn't any single specification. It's how all of the smaller updates come together once you actually look through the goggles. The night vision image shows better-controlled edge distortion and less chromatic aberration. The thermal channel starts faster, the UI is cleaner, and the fusion image shows more detail. More importantly, the lower perceived latency makes the thermal overlay track movement more closely, giving the FB20 a smoother and more natural feel when you're actually moving with the system. Outline Mode also produces finer contours, while the addition of Red Hot gives users another way to highlight warm targets.

That doesn't mean every change goes in the same direction. There are two differences worth knowing about: the FB20's built-in IR illuminator is weaker than the one on the original FB, and the FB20 does not offer the FB's standalone thermal-only viewing mode. Neither of these points changes what we found in the areas that matter most to the FB20's core viewing experience. Compared with the previous generation, the FB20 delivers cleaner night vision optics, a more refined thermal-fusion image, lower perceived fusion latency, and a more polished interface.

And that may be the best way to understand the FB20. It's not about one headline spec being dramatically better. It's about the system feeling more refined once you're actually behind the eyepieces.

For night vision users who are especially interested in analog-plus-thermal fusion, that's where the FB20's improvements become easiest to appreciate.

Which difference would matter most to you in actual use: cleaner night vision optics, smoother fusion, or the improved Outline Mode?