lens-dat

lens with infrared

inside of the lens

camera lens

1G6P structure

Front (facing object)
────────────────────────────
1 × Glass lens (G)
6 × Plastic lenses (P)
Spacer rings
Long rear barrel (tube structure)
Rear protective window (your breakable piece)
M12 metal housing

in chinese 

前方（朝向物体）
─────────────────────
| 第1片：玻璃透镜（1G 的 G，即唯一一片玻璃） |
| 第2片：塑料透镜（P）                         |
| 第3片：塑料透镜（P）                         |
| 第4片：塑料透镜（P）                         |
| 第5片：塑料透镜（P）                         |
| 第6片：塑料透镜（P）                         |
| 第7片：塑料透镜（P）                         |
─────────────────────
| 后组保护片（可被损坏的那片，多叫 Shield 或 IR） |
| IR-cut filter（红外截止滤光片） *
| Spacer（间隔环）                              |
| Rear Barrel（后镜筒）                          |
─────────────────────
传感器

lens structure

1. Glass + plastic lenses

  • 1 glass lens in the front
  • 6 plastic lenses behind
  • Held by the long tubular structure (rear barrel)

2. Rear Barrel ("the long tube inside")

  • The long cylindrical module inside the metal housing
  • Holds and aligns all lenses
  • Controls internal light path
  • Not itself a lens

3. Rear Protective Window (the breakable piece)

  • Flat optical-grade glass or clear polymer
  • Always placed at the very back of the lens
  • Easy to remove or break
  • Does not change FOV or focus significantly
  • Only protects, not part of the lens formula

What Happens if You Remove the Protective Window?

✔ Image still works normally

Because it is not part of the optical design.

✔ More dust risk

Dust may settle on the last lens surface, causing spots.

✔ Last optical element becomes exposed

Plastic lenses scratch very easily.

✔ You may need to improve sealing

Especially if you plan to waterproof the lens.

🟥 (A) IR‑Cut Filter (Infrared Cut Filter)

Most M12 lenses have a small IR‑cut piece near the sensor:

  • IR‑cut (infrared cut filter)
  • Very thin
  • Looks like glass
  • Breaks if pressed
  • Shows a slight blue‑green reflection
  • Purpose: block infrared light to improve white balance and color accuracy

📌 Note: this is the most common “fragile small lens.”

If you break it:

  • Daytime colors shift toward pink / red
  • Night view becomes brighter
    (Many night‑vision cameras intentionally omit this filter.)

lens selection

Specifications - M12 小型 3.9mm 焦距、F1.0 大光圈镜头

  • Aperture (F No.): 1.0 ±10%
  • Focal length (焦距): 3.9 ±5%
  • Optical back focal length (Optical Back Focal Length): 3.94 ±0.2 mm (in air)
  • Mechanical back focal length (Mechanical Back Focal Length): 3.85 ±0.2 mm (in air)
  • Total lens length (TTL): 22.24 ±0.2 mm (in air)
  • Image circle (像面大小): Ø6.9 mm (MAX)
  • Lens structure (镜片构成): 1G6P — note: if the first element is a plastic lens, wipe with alcohol only up to 3 times
  • Mount (接口): M12 × P0.5
  • Lens-to-base clamp torque (镜头与底座螺纹配合扭力): 60–600 gf·cm
  • Minimum object distance (近摄距 / M.O.D): 2 m
  • Resolution (解像标准): 3840 × 2160 (8MP)
  • Suggested tilt tolerance of sensor packaging: ≤ 5' (minutes)
  • Weight: /

Field of view (FOV) — sensor size / sensor dimensions (mm)

  • 1/2.7" — 5.760 × 3.240 × 6.609
    • H / V / D (水平 / 垂直 / 对角): 88.1° / 47.5° / 104.1°
  • 1/2.8" — 5.568 × 3.132 × 6.388
    • H / V / D: 84.6° / 45.9° / 100.0°
  • 1/2.9" — 5.376 × 3.024 × 6.168
    • H / V / D: 81.3° / 44.3° / 95.5°

Optical characteristics (by sensor size)

  • Optical distortion:
    • 1/2.7": -34.0%
    • 1/2.8": -32.0%
    • 1/2.9": -29.0%
  • TV distortion (TVDistortion):
    • 1/2.7": -11.3%
    • 1/2.8": -10.4%
    • 1/2.9": -9.6%
  • Relative illumination:
    • 1/2.7": 40.6%
    • 1/2.8": 43.0%
    • 1/2.9": 45.5%
  • Chief ray angle (CRA):
    • 1/2.7": 11.2°
    • 1/2.8": 10.8°
    • 1/2.9": 10.5°

Operation

  • Focus (聚焦): Manual
  • Iris (光圈): Fixed
  • Environmental & Safety (环保 & 安全): RoHS

Notes:

  • The first optical element may be plastic; if so, clean carefully and limit alcohol wipes to 3 times.

specs

ref

Table of Contents

https://www.electrodragon.com