Perspective

From ZBrush Info

The perspective management has been improved in ZBrush 3.5 and is now more consistent when switching from one SubTool to another.

You can define the Focal Length by modifying the slider and activating the Align to Object option, which makes ZBrush align the Scale / 3D Zoom operation to the current tool.

This button and these parameters are located in the Draw palette and a copy of the button is also on the right Shelf, located at the border of the document.

Shortcut: P