The perspective image of the punched sheet metal makes the hole diameters at top and bottom appear different. The bottom hole is partially hidden, as well.

Using telecentric lighting and imaging the top and bottom hole diameters appear the same size without perspective covering.

Due to the diffuse reflection in the glass the glass handle appears as a light source of its own. This results in a low contrast in brightness compared to the primary source of light.

In the parallel primary ray path of lighting and optics the glass handle works as a cylindrical lens and thus appears with high contrast.

With perspective imaging using an entocentric objective only few honeycomb profiles can be seen.

From the telecentric perspective all honeycomb profiles of the ceramic body (100 mm in height) can be tested for permeability.

The diffuse lighting makes edge recognition impossible; size and distance influence the width of this lowcontrast area.

Telecentric lighting and imaging results in high-contrast object edges.