384 vs 640 Thermal Sensors: What the Numbers Really Mean
384 or 640? It's the question that decides most thermal scope purchases, and the marketing answer ("640 is better") is misleading. The truth is more useful. At the same lens, a 384 and a 640 reach about the same distance. What changes is the field of view. This guide explains what the numbers really mean, so you can buy for the way you hunt and not the bigger sticker.
The short answer
For a given focal length and pixel pitch, a 384 and a 640 sensor give you roughly the same detection and identification distance. The 640 shows a wider field of view, so more of the paddock in frame, which is better for scanning and keeping moving game in view up close. The 384 shows a narrower, more magnified slice, and costs less. So it's not "640 sees further". It's "640 sees wider, 384 sees tighter for the money".
What the numbers actually mean
384×288 and 640×512 are pixel counts: how many detector elements the sensor has. Alongside that is pixel pitch (measured in microns, µm), which is the size of each pixel. Pitch sets the angular detail per pixel. Pixel count sets how much of the scene the sensor covers. Two sensors with the same pitch on the same lens resolve the same fine detail per pixel. The 640 just covers more area because it has more pixels.
That's the heart of it: more pixels means more scene, not more reach. Detection distance comes from the lens and the pitch, and both sensors can share those.
Same lens, same range, wider view
Put a 384 and a 640 with the same pixel pitch behind the same lens and you get the same pixels on the animal at distance, so detection and identification land at similar ranges. The difference you see straight away is the field of view. As a worked example, with 12µm pixels on a 50mm lens a 640 shows roughly an 8.8°×7° field of view, while a 384 shows about 5.3°×4°. Noticeably narrower, and so more magnified at base.
Neither is better on its own:
| 384 sensor | 640 sensor | |
|---|---|---|
| Field of view (same lens and pitch) | Narrower | Wider |
| Base magnification | Higher (more zoomed in) | Lower |
| Detection and ID distance | Similar | Similar |
| Scanning and awareness of what's around | Tighter, easier to lose moving game | Wider, easier to track |
| Value | More reach per dollar | Costs more |
So which should you choose?
- Go 640 if you scan a lot, hunt mobile game like pigs in mobs, or want to see as much as possible and the easiest picture to read. The wide field of view keeps moving animals in frame and makes identification more confident at distance.
- Go 384 if you want the most capability for your money and you mostly take deliberate shots at range, where the naturally narrower, more magnified view works in your favour. It picks up game just as far on the same lens.
And don't forget pixel pitch. A smaller pitch (12µm) packs the detail tighter for sharper distant edges but a narrower view, while a bigger pitch (17µm) collects more energy per pixel, which can help on low-contrast nights. Compare lens, pixel count and pitch together, not the resolution number on its own.
FAQ
Is a 640 thermal scope better than a 384?
Not across the board. At the same lens and pixel pitch they detect and identify at similar distances. The 640 gives a wider field of view and easier scanning. The 384 gives a more magnified view for less money. Which one is better depends on how you hunt.
Does a 640 sensor see further than a 384?
No, not on its own. Reach is set by the objective lens and pixel pitch. A 640 mainly widens the field of view. See our guide on detection range and lens size.
What does pixel pitch (12µm vs 17µm) change?
Pitch sets the detail per pixel and affects field of view and sensitivity. Smaller pitch (12µm) means finer distant detail and a narrower view. Bigger pitch (17µm) means more energy per pixel, which can help in poor contrast. It's as important as the resolution count.
If they reach the same distance, why buy a 640?
For the wider field of view and easier identification across a broader scene. That's genuinely valuable for scanning and for moving game. Just don't buy it expecting extra range. Buy it for the view.
Related: Detection Range and Lens Size, Why Digital Zoom Degrades Your Image, Thermal Scopes, Best Thermal Scopes 2026 and How Thermal Imaging Works.
Related reading: thermal pixel pitch (12µm vs 17µm) and base magnification vs field of view.