This lens has a lot in common with the original AT-X model, which was launched back in 2006. Indeed, the optical path appears to be identical, based on nine elements in eight groups and featuring two aspherical glass elements and two Super-Low Dispersion glass elements.
The build is compact, but the inner barrel extends as you reduce the focus distance from infinity towards the shortest focus setting. Even so, the working distance between the front of the lens and the subject is pretty respectable in full macro mode, at 11.5cm.