Pixel size at specimen plane calculator

The sensor's physical pixel size, the objective magnification, any intermediate factor (camera adapter, Optovar) and the binning give the pixel size at the specimen plane and the number of pixels per micrometre.

Display zoom plays no part: enlarging an image on screen adds no information.

Sensor pixel

physical size of a photosite, fixed by the camera (typically 3 to 11 µm).

Pixel at specimen plane

the portion of specimen a pixel covers after demagnification by the optics; it sets the sampling.

Total optical magnification

the objective multiplied by any intermediate optical element (0.5× or 0.63× camera adapter, non-standard tube lens, Optovar).

Binning

grouping neighbouring sensor pixels before readout. Binning 2 doubles the pixel width at the specimen and improves the signal-to-noise ratio.

The calculation assumes the stated magnifications are exact. Manufacturing tolerances, a tube lens whose focal length differs from the maker's design, or a misidentified adapter can introduce a few percent of deviation. A stage micrometer gives the reference calibration.

Optical resolution depends only on wavelength and numerical aperture. Pixel size sets how finely it is recorded: too fine a pixel makes images heavier, too coarse a pixel loses information. The ratio between the two is handled by the Nyquist sampling calculator.