Astranto

Your practical guide to observing the night sky, step by step.

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Astrophotography pixel scale calculator

Enter the pixel size of your camera sensor and the focal length of your instrument to get the sampling in arcseconds per pixel.

Atmospheric turbulence limits the detail you actually capture, whatever the figure. The pixel size is in the specifications of the camera sensor. With a reducer or a Barlow lens, enter the resulting focal length.

Enter your values, then calculate.

Method and limitations

Sampling in arcseconds per pixel = 206.265 × pixel size in micrometres ÷ focal length in millimetres. The constant 206.265 comes from the number of arcseconds in a radian (206 265) divided by 1 000 to go from micrometres to millimetres. The result is shown to two decimal places.

Sources

No external reference is documented for this calculation; its method and limitations are described above.

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