The Fuji 1655 is the same 28 from 16 to 55 While the Fuji 1855 is f/28 only at the 18mm end, when you twist and go to 55 it goes to f/4 When zooms are not constant apertures, and you twist the barrel the exposure WILL change because it is slower at the 55 end It is not the case with the 1655, it's a fast 28 from 16 to 55 Manufacturer description The FUJINON XF1655mmF28 R LM WR is a weatherresistant standard zoom lens with a 2484mm equivalent focal range that offers users the classic zoom range with a constant F28 in the market today The XF1655mmF28 R LM WR uses 14 sealing points for a durable, weatherresistant and dustproof design that make it the perfect The 1655mm f/28 R LM WR lens is what Fujifilm calls their "flagship standard zoom" Reminder, R means it has an aperture ring, LM means the lens has a linear motor, and WR means that the lens is built to be weather resistant The lens design has 17 elements in 12 groups Three of those elements are aspherical glass, three a