Fixed zoom: 0.7X,1X,2X,3X,4X,5X,6X,8X, WD refer to details
Telecentric Lens is that placed aperture diaphragm on image space focal plane of optical system.
When aperture diaphragm on image space focal plane, even object distance changes and image distance changes, image height doesn’t changes, then object size of measure will not change.
Telecentric Lens is applied in industry precision measurement. Distortion is very small. High-powered one can have no distortion.