熱鏡頭焦距與分辨率

Q: Q2: Does a short focal lens work better for close-range use?

Yes, short lenses provide a wide field of view, ideal for near-range monitoring.

熱鏡頭焦距與分辨率

當選擇一個 熱成像相機鏡片, many users focus on focal length — for example, choosing between 4毫米, 12毫米, 35毫米, or 50mm 鏡片. 然而, 該 sensor resolution (such as 320×240 or 640×480) is equally important. The combination of focal length and resolution directly determines how far and how clearly your thermal camera can see.

4mm 6.8mm camera lens for thermal imaging camera — 4mm 6.8mm 熱像儀鏡頭

1. The Core Relationship: Focal Length and Pixels

焦距 determines how far the lens can “see” — a longer focal length provides higher magnification and a narrower field of view.
解析度 (pixel count) determines how detailed the image appears — more pixels mean finer details.

簡而言之:

A longer focal length magnifies the image, while higher resolution ensures that the magnified image remains sharp.

If the sensor has too few pixels, increasing the focal length won’t improve clarity — it just zooms in on fewer pixels.

2. Practical Examples

鏡頭焦距	Sensor Resolution
4毫米 + 320×240	Wide view, suitable for close-range observation.
35毫米 + 320×240	Sees farther, but image appears pixelated due to low pixel density.
35毫米 + 640×480	Clear and detailed long-distance image — optimal combination.

一個 low-resolution sensor 與一個 long focal length lens can make distant objects appear larger but not clearer.
一個 high-resolution sensor can fully utilize a long focal length lens to achieve both range and image quality.

3. Why Matching Matters

Choosing the wrong combination can lead to:

Blurry or pixelated images when using a long focal lens on a low-resolution sensor.
Too wide field of view with insufficient target detail when using a short focal lens.

To get the best performance, the lens and sensor must be balanced based on your target size, 距離, 和 應用程序方案.

4. Recommended Combinations

應用程序方案	Recommended Focal Length	Recommended Resolution
Close-range monitoring / 檢查	4mm – 6.8mm	320×240
Mid-range detection / Vehicle use	12mm – 25mm	640×480
Long-range observation / 安全 / 無人機	35mm – 70mm	≥640×480

5. Key Takeaway

Focal length determines how far you can see; resolution determines how clearly you can see.
To achieve the best thermal imaging results, both must be chosen together.