Tech note: camera resolution and field of view — choose right without overspending or slowing the line
Detection capability is roughly 3–5 times the resolution; doubling resolution means four times the images. A table of fields of view for 5 MP to 25 MP cameras at different resolutions, plus trade-offs from real projects.
“How many megapixels do we need?” is the first question in every vision project. The answer depends on three things: the smallest defect to catch, the area to cover and the line takt.
Three rules of thumb
- Detection capability is about 3–5 times the resolution (size per pixel). At 10 μm, defects of about 0.03–0.05 mm can be found
- Doubling resolution quadruples the number of images for the same area, and scan time rises accordingly
- Higher magnification means shallower depth of field. In one test a 10× lens gave 0.25 μm but could not cover the part's height, while a 5× lens at 0.5 μm could
Megapixels, resolution and field of view
- 5 MP: 30 μm → 73.4 × 61.4 mm; 50 μm → 122.4 × 102.4 mm; 20 μm → 49.0 × 41.0 mm
- 12 MP: 30 μm → 122.9 × 90 mm; 34.5 μm → 141.3 × 103.5 mm
- 20 MP: 30 μm → 135.1 × 135.1 mm
- 25 MP: 30 μm → 153.6 × 153.6 mm; 25 μm → 128 × 128 mm; 5 μm → 25.6 × 25.6 mm
- 2.3 MP: 30 μm → 57.6 × 36 mm; 20 μm → 38.4 × 24 mm
Trade-offs from real projects
- Wafer appearance: 2.5 μm captures everything, but 5–9 μm is recommended, cutting a full-wafer scan from tens of seconds to about 15 s
- Heat spreaders: higher resolution made defects clearer — and the blasting texture too, increasing false calls
- 5 mil dies: 1.25 μm vs 1.5 μm differs by about 1.2×, with more detail and easier alignment, but little difference in sharpness
- Large products in continuous motion: use a line-scan camera that builds the image line by line
Not sure what to choose? Send samples and we will image them at different resolutions so we can decide together.
