Originally Posted by umop-apisdn
What is the point of lenses like this? Trying to photograph the hubble or something
That lens is the 400mm f2.8 L glass with IS (image stabilization)
Generally used for auto sports, wildlife, and things you need to reach for. There are much bigger lenses available but that is probably one of the more common in this field and worth the money ($6k +/- average).