Pixel size at specimen plane calculator

Total optical magnification is the product of the objective magnification and any real intermediate factor. A display zoom is never part of it: enlarging an image on screen adds no information.

Sensor pixel

· physical size of a photosite, fixed by the camera (typically 3 to 11 µm). It never changes.

Pixel at specimen plane

· the portion of specimen a pixel covers once the image is demagnified by the optics. This is what determines 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 creates a pixel twice as wide, hence twice as coarse at the specimen, in exchange for a better signal-to-noise ratio.

This calculation assumes the magnification stated by each component is exact. In practice, calibration with a stage micrometer remains the reference: 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. The result here is a design estimate, never a measurement.

Optical resolution depends only on wavelength and objective numerical aperture: no sensor improves it. Pixel size only describes how finely that resolution is recorded. A pixel finer than needed makes images heavier without adding anything; a pixel too coarse loses genuinely available information. What matters is the ratio between the two, see the Nyquist sampling calculator.