The F microscope body was released in 1960.
Based on the E model, the F microscope body featured improved fine motion sensitivity in the focusing mechanism (up to 0.0005 mm) and easier focusing at high magnifications.
The E and F models were developed further in 1963.
The light source, which had previously been mounted at the front and in an inclined position, was built into the mirror body. This was the first ever microscope with a built-in light source.