The most convenient portrait monocle for APS-C cameras.
This monocle can be called "portrait for crop-matrix cameras" for several reasons.
First, in terms of its equivalent focal length of 90 mm.

Secondly, it has practically no spatial optical distortions. It can be used for large-scale portrait photography with focus at a minimum distance.
Third, it has a moderate level of contour sharpness, which allows you to fully use it as a tool of "optical retouching".