A transparent sheath (user supplied) can be used to measure detached leaves and other objects that are too fragile to pass through the scanning head. When measuring samples that are highly irregular or small, such as damaged leaves with complex margins, roots, thin grasses, etc., accuracy can be improved by changing the 3000 threshold to 80. This compensates for light lost as it passes through the sheath, and sets the edge counting criteria back to near 50%.