3.76 µm pixels at 480 mm
206.264806 × 3.76 / 480 = approximately 1.6157 arcsec/pixel. One pixel represents this angle; the number does not establish sharpness.
Load this example in the calculatorPixel-scale calculator
Convert camera pixel pitch and telescope effective focal length to angular image scale in arcseconds per pixel.
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What this calculation tells you
Pixel scale describes the angular size represented by one pixel near the optical axis. It is a conversion between camera geometry and sky angle, not a measurement of the resolution your full imaging system actually delivers.
Inputs and workflow
- Enter effective focal length in millimetres, accounting for the optical configuration. A plate-solved image can check a nominal focal-length estimate after a reducer or amplifier.
- Enter physical pixel pitch in micrometres. Do not enter total sensor width or megapixels. For a 2×2 binned output, use twice the native pitch only if the input has not already been adjusted for binning.
- Use the output in arcseconds per pixel when comparing seeing, guiding measurements or image sampling. Check whether the acquisition software has already multiplied pixel pitch by the binning factor; applying it twice gives the wrong scale.
Formula and units
Scale (arcsec/pixel) ≈ 206.264806 × pixel pitch (µm) / focal length (mm). The factor converts radians to arcseconds and micrometres to millimetres.
Worked examples
Same pixels at 960 mm
The scale is approximately 0.8079 arcsec/pixel. Doubling focal length halves the angular size per pixel, without promising twice the resolved detail.
Load this example in the calculator2×2 output bins from 3.76 µm pixels at 480 mm
A two-pixel-wide output bin uses 2 × 3.76 = 7.52 µm effective pitch: approximately 3.2315 arcsec per output pixel. This changes the output sampling, not the telescope optics, and does not assert a camera-specific noise benefit.
Load this example in the calculatorLimits before using the result
This is the small-angle plate-scale approximation near the axis. It does not model distortion or field-dependent image scale.
Seeing, focus, diffraction, tracking and processing can limit actual detail. There is no universal best arcsec/pixel threshold in this calculator; use the separate sampling tool for an explicit FWHM comparison.
Sources and method notes
- Atik: image-scale calculation
Source for the pixel-size/focal-length conversion. Its ideal-scale purchasing thresholds are not adopted here.
- Siril: plate solving and image sampling
Official documentation describes focal length and pixel-pitch inputs, plate-solved estimates, and the two FITS binning conventions. Check the convention before multiplying pitch.
Calculation notes maintained by AstroGearFit. Updated October 13, 2026. Examples are numerical demonstrations, not hands-on equipment tests. The method notes are currently in English; the existing interface language selector remains available.
Choose a calculation
Five focused checks with reproducible examples and explicit limits. These tools do not certify a complete equipment combination.
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