Camera Angular Resolution Calculator

Example data table

Example values are illustrative; your exact results depend on lens, sensor, and wavelength.

Formula used

1) Pixel angular scale (pixel-limited resolution)

The per-pixel angular scale estimates how much sky or scene angle maps to one pixel: arcsec/px = 206.265 × (pixel_size_µm / focal_length_mm). The constant 206.265 converts radians to arcseconds using small-angle geometry.

2) Field of view

Sensor width and height are derived from pixel count and pixel size: sensor_mm = pixels × pixel_size_µm / 1000. Then the angular field of view uses: FOV = 2 × arctan(sensor / (2 × focal)).

3) Diffraction limit (Rayleigh criterion)

The optics can also be limited by diffraction: θ = 1.22 × λ / D, where λ is wavelength and D is aperture diameter. With an f-number, D = focal / f_number.

How to use this calculator

1. Enter your lens focal length and camera pixel size.
2. Fill in image resolution in pixels (width and height).
3. Add your f-number and a representative wavelength (550 nm is typical green light).
4. Optionally add distance to estimate linear detail per pixel.
5. Press Calculate to see results above the form.
6. Use Download CSV or Download PDF to save outputs.

Camera angular resolution guide

1) What angular resolution means

Angular resolution is the smallest angle your camera system can represent as distinct detail. Two limits compete: the sensor’s pixel sampling and the optics’ diffraction. Real images include focus error and motion blur, so usable resolution can often be worse than theory.

2) Pixel scale and the 206.265 constant

Pixel scale converts pixel size and focal length into angle per pixel. A common approximation is arcsec/px = 206.265 × pixel(µm) ÷ focal(mm). Example: 4.3 µm at 400 mm is ~2.22 arcsec/px. 3.76 µm at 800 mm is ~0.97 arcsec/px.

3) Focal length and pixel pitch tradeoffs

Doubling focal length halves arcsec/px, but also narrows field of view. Smaller pixels also reduce arcsec/px, yet may increase noise at equal exposure. Many modern cameras fall near 3–5 µm, while compact sensors can be around 1.2–2.0 µm and some larger sensors exceed 6–8 µm.

4) Field of view from sensor dimensions

Field of view depends on sensor size and focal length. Sensor width and height can be derived from pixel count and pixel size, then applied to FOV = 2 × arctan(sensor ÷ (2 × focal)). A 25.8 mm wide sensor at 400 mm is only a few degrees, while a 35–36 mm width at 24 mm can exceed 70°.

5) Diffraction limit and f-number

Diffraction sets a best‑case optical limit: θ = 1.22 × λ ÷ D. With an f-number, D = focal ÷ f-number, so lower f-numbers increase aperture diameter. At 550 nm, an 80 mm aperture is about 1.7 arcsec, while 50 mm is roughly 2.7 arcsec.

6) Sampling, Nyquist ratio, and sharpness

Capturing optical detail typically needs sampling at about two pixels across the diffraction spot. The Nyquist ratio here compares your pixel scale to half the diffraction limit. Around 1.0 is balanced; above about 1.2 indicates undersampling (pixels bottleneck), and below 0.9 suggests oversampling (optics or conditions bottleneck).

7) Estimating detail at a real distance

If you enter distance, the tool estimates linear resolution using small‑angle geometry. As a quick reference, 1 arcsec spans about 4.85 mm at 1 km. So 2.2 arcsec/px is roughly 10.7 mm per pixel at 1 km for planning shots.

FAQs

1) What if I don’t know my pixel size?

Use pixel(µm) = sensor_width(mm) × 1000 ÷ pixels_width. If you only know a sensor format name, look up the sensor width in millimeters, then compute pixel size from your image width in pixels.

2) Which wavelength should I enter?

550 nm is a common visible-light reference. For blue use ~450 nm, for red ~650 nm, and for near‑IR ~850–940 nm. Longer wavelengths make diffraction slightly worse.

3) Why does the diffraction limit worsen at higher f-numbers?

Higher f-numbers mean a smaller aperture diameter at the same focal length. Smaller apertures increase diffraction blur, increasing the minimum resolvable angle. Stopping down can still improve sharpness by reducing aberrations.

4) Does arcsec per pixel apply to terrestrial scenes?

Yes. Arcseconds are just angular units, so the mapping works for landscapes and targets too. For real outcomes, also account for haze, turbulence, stabilization, focus accuracy, and shutter speed.

5) What does the Nyquist ratio tell me?

It compares pixel scale to half the diffraction limit. Near 1.0 is balanced. Higher values indicate undersampling, where pixels limit detail. Lower values indicate oversampling, where optics or conditions limit detail more than pixels.

6) How can I improve angular resolution?

Use longer focal length, smaller pixels, or a larger aperture diameter (lower f-number at the same focal length). Stabilize the camera, focus carefully, and shoot in steady air to approach theoretical limits.