This lens is a monster - it weighs over 4 kg, is 85 cm long when fully extended, and the front element is 90 mm in diameter! A tripod is a must, and a sturdy head is required because it's dreadfully front-heavy. It's an old lens, made about 30 years ago, but it's still usable on my modern *ist-D. It's also surprisingly sharp even wide open; better than my A400/5.6 in fact.