4 Things to Know About Night Vision Goggles

If you just bought new night vision goggles (NVG) and think they’re defective. Or, you're still wondering how do night vision goggles work? Read this guide before you consider returning them. Many people buy their first night vision device (NVD) and think it’s defective because they see black spots in their vision, the image is too dark or distorted, or have concerns about the integrated IR illuminator. While it’s possible you received a defective product, that’s most likely not the case. In this guide, we’ll break down some of the most frequently asked questions about night vision goggles, monoculars, binoculars, and scopes and offer solutions on how to fix common night vision problems.

Black Spots and Blemishes in Night Vision Goggles

Most movies and TV shows don’t realistically portray how night vision goggles work. Of course, throwing a night vision filter on a high-definition video will look 100% crisp and clear throughout, but that’s not always the case with real night vision optics, especially if they’re Gen 1 night vision. One thing popular culture doesn’t properly display is dark spots in your view while using night vision goggles. 

Black spots in night vision devices are called artifacts and commonly occur during manufacturing. You’ll mainly see them while looking at clean, plain backgrounds. However, these night vision artifacts are barely noticeable when using them in the field or on the hunting grounds. 

Now, it is possible that you received an image intensifier tube that is not up to standards, but that is highly unlikely. Try using your NVG in a detailed outdoor setting to see if the dark spots are still obstructing your view. If so, you should contact the manufacturer and explain your problem. DO NOT attempt to open the device yourself. In most cases, this will void any warranty or possibility of returning the defective item. 

Distortion and the Fishbowl Effect with NVG 

Another common issue we see with night vision goggles involves complaints of image distortion in the form of a fisheye (or fishbowl) effect. The fisheye effect is when you look through your night vision device and see curvature around the edges that resembles a panoramic picture. What a lot of people don’t realize is that most Gen 1 night vision goggles have this effect due to lower optical quality than Gen 2 or Gen 3 night vision devices. 

Most night vision optics are expensive, and Gen 2 and Gen 3 NV come at an even steeper price than Gen 1. However, if you want the best quality from your NVG, then it is worth it to invest in a Gen 2 or 3 night vision device. If you experience this optical distortion with Gen 2 or Gen 3 night vision, try adjusting the objective focus. Switching between close and long-range viewing may result in incorrect adjustments to your NVG, and adjusting the focus can help alleviate or completely fix night vision image distortion.

Night Vision Goggles: Automatic vs. Manual Gain Control

Some folks complain that their view is too dark while using a new night vision optic. In most of these cases, the NVG has a manual gain control (also known as variable gain control) instead of automatic gain control. Long story short, gain affects how bright or dark your image will be while using night vision goggles. 

With auto gain control, your night vision device uses a sensor to automatically adjust the brightness level to provide the best view based on your ambient lighting conditions. On the other hand, manual (variable) gain control allows you to manually adjust the brightness level to your liking. While this is great for customizing your viewing experience, you need to know how to adjust the manual gain control knob to match your environment. 

Check the features and specs of your NVD to see what type of control it has. If it mentions manual or variable gain control, you now know that you need to adjust the brightness yourself to get a brighter view. However, if your device is only equipped with an automatic brightness control setting and your view is too dark, you may have a defective model and should contact the manufacturer for more information. 

Night Vision Goggles and IR Illuminators 

Infrared (IR) light is not visible to the naked eye, but it can be detected by night vision devices. Night vision goggles use infrared illuminators to enhance the brightness of your image without giving away your position. Many NV optics come equipped with a built-in IR illuminator, but sometimes, this integrated IR illuminator isn’t very powerful. 

Even if your night vision device comes with a built-in IR illuminator, it may be worth buying an add-on IR illuminator if you’re dissatisfied with the included one’s performance. Infrared accessories can greatly enhance your night vision experience. If you own a night vision rifle scope, you can mount an IR laser sight to your weapon that offers the same advantages as red and green lasers, but the beam can only be seen by a night vision device. 

Like Night and Day

Once you figure out how to use night vision goggles correctly, your viewing experience will be a huge step up from before. We covered four of the most popular items on our night vision FAQ list and explained why they occur. 

• You now know why some night vision optics show black spots and how to reduce them. 
• You learned that some Gen 1 night vision devices normally have slight image distortion and that adjusting your objective focus can help reduce this fisheye effect.
• You should now understand the difference between manual and automatic gain control and how it impacts image brightness. 
• And finally, you learned about IR illuminators and why they’re a key component to a great night vision setup. 

Night vision goggles are complicated devices, and it may take some time to figure out how they work. We hope this guide was able to answer some of your questions about night vision and help you fix common NV issues. If you want to learn more about night vision, check out our guides on How Night Vision Works and The Difference Between Night Vision and Thermal Imaging.