[Brightcolours]

 

It's a big lens especially given it's designed for mirrorless.

For instance, the Canon equivalent is slightly smaller and lighter while the Pentax being much smaller (although not great optically; it's got WR however) :

• Fuji: 76 x 98mm, 490g
  
• Canon: 77 x 96mm, 480g
  
• Pentax: 74 x 76mm, 405g
  

 

The Canon is designed for 44mm distance from the sensor, the Fuji for 18mm. That makes the whole back part of the optics very different in design, and makes the Canon, when you include the extra distance, bigger (I bet they are similar at 135mm).  The width is similar (just 2mm in it, same filter size), as is the weight. Not surprising the Canon and Fuji are about the same size (same front lens design).

 

The Pentax is a weak lens... The Fuji is weather sealed too.