This lens is for CROP SENSOR ONLY. Dont try it on Full frame, otherwise you would damage camera sensor.
BTW, 400/28.8 is x1.6(crop sensor ratio) of 250/18, so zoom will be same = 13.89x
WTF you won't damage
the camera sensor. Your images will just come out with extreme vignetting. Please explain how taking a picture with this lens on a full frame camera would DAMAGE
the image sensor.