The optical formula boasts 21 elements in 14 groups, of which five are low-dispersion and one is super low-dispersion glass, designed to combat chromatic aberration. All this makes for a large lens, coming in at just under 8.5 inches long at its shortest focal length and 10.75 inches racked out at 400mm. This is roughly equivalent in size to similar optics for DSLRs that we’ve tested: Canon’s 100–400mm f/4.5–5.6L IS (from back in 1999—we haven’t tested the 2014 update); Nikon’s 80–400mm f/4.5–5.6 VR; and Tokina’s 80–400mm f/4.5–5.6. Of the four, this new zoom is the longest at both its shortest and longest focal lengths, though comparable in diameter to the Nikon and Canon. Tokina’s zoom is considerably shorter, measuring just over 5.25 inches at its base 80mm focal length. Considering the relative compactness of Fujifilm’s camera bodies, the overall effect seems rather outsized.